Group IIIA nitride growth system and method

ABSTRACT

A system and method for growing a gallium nitride (GaN) structure that includes providing a template; and growing at least a first GaN layer on the template using a first sputtering process, wherein the first sputtering process includes: controlling a temperature of a sputtering target, and modulating between a gallium-rich condition and a gallium-lean condition, wherein the gallium-rich condition includes a gallium-to-nitrogen ratio having a first value that is greater than 1, and wherein the gallium-lean condition includes the gallium-to-nitrogen ratio having a second value that is less than the first value. Some embodiments include a load lock configured to load a substrate wafer into the system and remove the GaN structure from the system; and a plurality of deposition chambers, wherein the plurality of deposition chambers includes a GaN-deposition chamber configured to grow at least the first GaN layer on a template that includes the substrate wafer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority benefit, under 35 U.S.C. § 119(e), ofU.S. Provisional Patent Application No. 62/342,026 filed May 26, 2016 byRobbie J. Jorgenson, titled “Low Temperature Gallium Nitride byMagnetron Sputtering/PVD Materials, Process and Equipment,” U.S.Provisional Patent Application No. 62/385,089 filed Sep. 8, 2016 byRobbie J. Jorgenson, titled “SYSTEM AND METHOD FOR DOPING GALLIUMNITRIDE DURING GROWTH BY PHYSICAL VAPOR DEPOSITION AND RESULTINGMATERIALS AND DEVICES,” U.S. Provisional Patent Application No.62/396,646 filed Sep. 19, 2016 by Robbie J. Jorgenson, titled “SYSTEMAND METHOD FOR DOPING GALLIUM NITRIDE DURING GROWTH BY PHYSICAL VAPORDEPOSITION AND RESULTING MATERIALS AND DEVICES,” U.S. Provisional PatentApplication No. 62/412,694 filed Oct. 25, 2016 by Robbie J. Jorgenson,et al., titled “GALLIUM NITRIDE GROWTH BY SPUTTERING AND RESULTINGMATERIALS AND DEVICES,” and of U.S. Provisional Patent Application No.62/462,169 filed Feb. 22, 2017 by Robbie J. Jorgenson, titled “GALLIUMNITRIDE GROWTH BY SPUTTERING AND RESULTING MATERIALS AND DEVICES,” eachof which is incorporated herein by reference in its entirety.

This application is related to prior:

-   -   U.S. patent application Ser. No. 15/294,558, titled “SYSTEM AND        METHOD FOR LIGHT-EMITTING DEVICES ON LATTICE-MATCHED METAL        SUBSTRATES” filed Oct. 14, 2016, and published as Application        Publication US 2017/0110626 on Apr. 20, 2017;    -   U.S. Provisional Patent Application No. 62/242,604, titled        “METHOD AND HYPER EMISSION GREEN LIGHT-EMITTING DIODE ON        LATTICE-MATCHED METAL SUBSTRATES FOR ADVANCED OPTICAL FIBER        NETWORKING” filed Oct. 16, 2015;        each of which is hereby incorporated by reference in its        entirety.

This application is also related to prior:

-   -   U.S. Provisional Patent Application No. 60/835,934, titled        “III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE        REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH        DEVICES, AND METHODS” filed Aug. 6, 2006;    -   U.S. Provisional Patent Application No. 60/821,588, titled        “III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE        REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH        DEVICES, AND METHODS” filed Aug. 7, 2006;    -   U.S. Provisional Patent Application No. 61/066,960, titled        “CURRENT-INJECTING/TUNNELING LIGHT EMITTING DEVICE AND METHOD”        filed Feb. 25, 2008;    -   U.S. Provisional Patent Application No. 61/610,943, titled        “METALLO-SEMICONDUCTOR STRUCTURES FOR III-NITRIDE DEVICES” filed        Mar. 14, 2012;    -   U.S. Provisional Patent Application No. 61/623,885, titled        “STRUCTURES FOR III-NITRIDE DEVICES” filed Apr. 13, 2012;    -   U.S. Provisional Patent Application No. 61/655,477, titled        “METAL-BASE TRANSISTORS FOR III-NITRIDE DEVICES” filed Jun. 4,        2012;    -   U.S. Pat. No. 7,915,624, issued Mar. 29, 2011, titled        “III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE        REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH        DEVICES, AND METHODS”;    -   U.S. Pat. No. 8,253,157 (a divisional of the application that is        now U.S. Pat. No. 7,915,624), issued Aug. 28, 2012, titled        “III-NITRIDE LIGHT-EMITTING DEVICES WITH REFLECTIVE ENGINEERED        GROWTH TEMPLATES AND METHODS OF MANUFACTURE”;    -   U.S. Pat. No. 8,890,183 (a divisional of the application that is        now U.S. Pat. No. 8,253,157), issued Nov. 18, 2014, titled        “III-NITRIDE LIGHT-EMITTING DEVICES WITH REFLECTIVE ENGINEERED        GROWTH TEMPLATES AND MANUFACTURING METHOD”;    -   U.S. Pat. No. 7,842,939, issued Nov. 30, 2010, titled        “CURRENT-INJECTING/TUNNELING LIGHT-EMITTING DEVICE AND METHOD”;    -   U.S. Pat. No. 8,865,492 (a divisional of the application that is        now U.S. Pat. No. 7,842,939), issued Oct. 21, 2014, titled        “METHOD OF FORMING CURRENT-INJECTING/TUNNELING LIGHT-EMITTING        DEVICE”; and    -   U.S. Pat. No. 9,608,145, issued Mar. 28, 2017, titled        “MATERIALS, STRUCTURES, AND METHODS FOR OPTICAL AND ELECTRICAL        III-NITRIDE SEMICONDUCTOR DEVICES”;        each of which is incorporated herein by reference in its        entirety.

There are multiple embodiments described herein, each of which can becombined with one or more other embodiments described herein and/orincorporated by reference. In some other embodiments, the presentinvention provides subcombinations that include most features of thevarious embodiments, but omit one or more features that are individuallyshown and described herein.

FIELD OF THE INVENTION

The present invention relates to the field of semiconductor devices andmethods of manufacturing semiconductor devices, and more specifically tomaterials, structures, and methods for growing Group-III-nitridedevices.

BACKGROUND OF THE INVENTION

Publication titled “Magnetron Sputter Epitaxy of Gallium Nitride on(0001) Sapphire,” by J. B. Webb, D. Northcott, S. Charbonneau, F. Yang,D. J. Lockwood, O. Malvezin, P. Singh, J. Corbett, Materials ScienceForum, Vols. 264-268, pp. 1229-1234 (1998) is incorporated herein byreference.

Publication titled “Thermal Expansion of Gallium Nitride,” by M.Leszczynski, T. Suski, H. Teisseyre, P. Perlin, I. Grzegory, J. Jun, S.Porowski, T. D. Moustakas, J. Appl. Phys., 4909 76 (8) (1994) isincorporated herein by reference.

Publication titled “Improved Understanding and Control of Mg-doped GaNby Plasma Assisted Molecular Beam Epitaxy,” by S. D. Burnham,dissertation at http://hdl.handle.net/1853/16228 (2007) is incorporatedherein by reference.

Publication titled “Stress Evolution During Growth of GaN(0001)/Al2O3(0001) by Reactive DC Magnetron Sputter Epitaxy,” by M.Junaid, P. Sandström, J. Palisaitis, V. Darakchieva, C-L Hsiao, P.O. Å.Persson, L. Hultman, J. Birch, J. Phys. D: Appl. Phys. 47, 145301 (2014)is incorporated herein by reference.

Publication titled “A route to Low Temperature Growth of Single CrystalGaN on Sapphire,” by Motamedi, Pouyan, Dalili, Neda, Cadien, Kenneth, J.Mater. Chem. C, 3, 7428-7436 (2015) is incorporated herein by reference.

Publication titled “X-ray and Raman Analyses of GaN Produced byUltrahigh-rate Magnetron Sputter Epitaxy,” by Minseo Park, J.-P. Maria,J. J. Cuomo, Y. C. Chang, J. F. Muth, R. M. Kolbas, R. J. Nemanich, E.Carlson, J. Bumgarner, Applied Physics Letters, 81, 1797 (2002) isincorporated herein by reference.

Publication titled “Structural Properties of GaN Layers Grown on Al₂O₃(0001) and GaN/Al₂O₃ Template by Reactive Radio-Frequency MagnetronSputter Epitaxy,” by Hiroyuki Shinoda, Nobuki Mutsukura, Vacuum, vol.125, pp. 133-140 (2016) is incorporated herein by reference.

Publication titled “Magnetron Sputter Epitaxy of GaN Epilayers andNanorods,” by Muhammad Junaid, Linköping Studies in Science andTechnology, Dissertation No. 1482, Linköping University (2012) isincorporated herein by reference.

Publication titled “Sputtering yield increase with target temperaturefor Ag,” by R. Behrisch and W. Eckstein, Nuclear Instruments and Methodsin Physics Research B, vol. 82, pp. 255-258 (1993) is incorporatedherein by reference.

Publication titled “Stress control in GaN grown on silicon (111) bymetalorganic vapor phase epitaxy,” by E. Feltin, B. Beaumont, M. Laügt,P. de Mierry, P. Vennéguès, H. Lahrèche, M. Leroux, and P. Gibart,Applied Physics Letters, 79, 3230 (2001) is incorporated herein byreference.

Publication titled “AlN/AlGaN superlattices as dislocation filter forlow-threading-dislocation thick AlGaN layers on sapphire,” by Hong-MeiWang, Jian-Ping Zhang, Chang-Qing Chen, Q. Fareed, Jin-Wei Yang, and M.Asif Khan, Applied Physics Letters, 81, 604 (2002) is incorporatedherein by reference.

Publication titled “Stress engineering with AlN/GaN superlattices forepitaxial GaN on 200 mm silicon substrates using a single wafer rotatingdisk MOCVD reactor,” by J. Su, E. Armour, B. Krishnan, Soo Min Lee, andG. Papasouliotis, Journal of Materials Research, vol. 30, issue 19, pp.2846-2858 (2015) is incorporated herein by reference.

U.S. Pat. No. 6,323,417 to Timothy J. Gillespie, et al., titled “METHODOF MAKING I-III-VI SEMICONDUCTOR MATERIALS FOR USE IN PHOTOVOLTAICCELLS,” issued on Nov. 27, 2001 is incorporated herein by reference.

U.S. Pat. No. 6,692,568 to J. J. Cuomo, et al., titled “METHOD ANDAPPARATUS FOR PRODUCING MHIN COLUMNS AND MHIN MATERIALS GROWN THEREON,”issued on Feb. 17, 2004 is incorporated herein by reference.

U.S. Pat. No. 6,784,085 to J. J. Cuomo, et al., titled “MIIN BASEDMATERIALS AND METHODS AND APPARATUS FOR PRODUCING SAME,” issued on Aug.31, 2004 is incorporated herein by reference.

U.S. Pat. No. 7,879,697 to P. I. Cohen, et al., titled “GROWTH OF LOWDISLOCATION DENSITY GROUP-III NITRIDES AND RELATED THIN-FILMSTRUCTURES,” issued on Feb. 1, 2011 is incorporated herein by reference.

SUMMARY OF THE INVENTION

In some embodiments, the present invention provides epitaxial atomiclayer sputtering (EALS) utilizing a solid gallium target (in some suchembodiments, the EALS includes magnetron sputtering). In someembodiments, the present invention produces films with two-dimensional(2D) step growth where columnar growth is avoided. Such a processenables high-quality Gallium Nitride (GaN) films that are lower inhydrogen and carbon. In some embodiments, unlike with Metal-OrganicChemical Vapor Deposition (MOCVD), metal organics are not required. Insome embodiments, the plasma used during the process lowers the requiredgrowth temperature (compared to MOCVD) and increases the growth rate(compared to Molecular Beam Epitaxy (MBE)) while still maintaininghigh-quality films.

In some embodiments, the present invention provides systems and methodsfor growing cost effective epitaxial materials of high quality that pushthe envelope of the current industry's capabilities. In someembodiments, such materials have larger epitaxial domains prior tocoalescence and a different density of misfit dislocations.

In some embodiments, the associated ion interaction makes the density ofdislocations self-annihilate (self-react) within a thinner filmthickness, as compared to the purely thermal environment of MOCVD.

Additionally, since there exists a thermal contraction difference (e.g.,due to different coefficients of thermal expansion (CTE)) between GaNand substrate, in some embodiments, when GaN is grown upon sapphire atlower temperatures than that of the temperatures used by MOCVD, thedegree of subsequent wafer bowing and wafer stress is reduced. Thissolves many problems of wafer cracking, epitaxy cracking,non-uniformities, the need for thicker sapphire substrates, and the needfor engineered wafer pockets in the MOCVD system for the subsequentactive region growth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method 101 for growing gallium-nitride(GaN)-based devices.

FIG. 2 is a schematic diagram of a system 201 for growing GaN-baseddevices.

FIG. 3 is a schematic diagram of a GaN structure 301.

FIG. 4 is a schematic diagram of a low-temperature group IIIA-nitridesputtering system 401.

FIG. 5A include schematic diagrams of a plurality 501 of growth modesthat illustrate different epitaxial growth modes according to someembodiments of the present invention.

FIG. 5B is a set 502 of atomic-force microscopy (AFM) images of GaNgrowth.

FIG. 6A is a table 601 of thicknesses (in nanometers) for the AlN andGaN layers set forth in GaN structure 301 of FIG. 3.

FIG. 6B is a continuation of table 601.

FIG. 7A is a table 701 showing the Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction (XRD) values (in arcseconds) forGaN produced according to some embodiments of the present invention.

FIG. 7B is a continuation of table 701.

FIG. 8A is a schematic diagram of a template and device epitaxy system801 for electronics and solid-state lighting (SSL).

FIG. 8B is a schematic diagram of a template and device epitaxy system802 for electronics and SSL.

FIG. 9 is a schematic diagram of a template and device epitaxy process901 for electronics and SSL.

FIG. 10 is a graph 1001 showing n-type carrier concentration (per cubiccentimeter) versus adatom mobility (cm²/V·s) for hafnium-doped galliumnitride produced according to some embodiments of the present invention.

FIG. 11 is a graph 1101 showing the X-ray diffraction (XRD) data for GaNproduced according to some embodiments of the present invention.

FIG. 12 is a schematic diagram of a GaN template structure 1201 forsubsequent LED epitaxial growth.

FIG. 13 is a schematic diagram of an epitaxial stack structure 1301 ofGEMM/GaN.

FIG. 14A is a graph 1401 of X-ray diffraction (XRD) data for GaNproduced according to some embodiments of the present invention.

FIG. 14B is a graph 1402 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 14C is a graph 1403 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 14D is a graph 1404 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 15 is a diagram 1501 of atomic-force microscopy (AFM) data for GaNon GEMM produced according to some embodiments of the present invention.

FIG. 16 is a graph 1601 showing a comparison between reflectivity ofGEMM/GaN produced according to some embodiments of the present invention(solid line) versus conventional AlN/GaN distributed Bragg reflectors(DBRs) (dotted line).

FIG. 17 is a graph 1701 of estimated sputtering yield for galliumnitride (GaN) versus temperature of the gallium target.

FIG. 18 is a schematic diagram of a sputtering system 1801.

DESCRIPTION OF PREFERRED EMBODIMENTS

Although the following detailed description contains many specifics forthe purpose of illustration, a person of ordinary skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the invention. Specific examples are used toillustrate particular embodiments; however, the invention described inthe claims is not intended to be limited to only these examples, butrather includes the full scope of the attached claims. Accordingly, thefollowing preferred embodiments of the invention are set forth withoutany loss of generality to, and without imposing limitations upon theclaimed invention. Further, in the following detailed description of thepreferred embodiments, reference is made to the accompanying drawingsthat form a part hereof, and in which are shown by way of illustrationspecific embodiments in which the invention may be practiced. It isunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.The embodiments shown in the Figures and described here may includefeatures that are not included in all specific embodiments. A particularembodiment may include only a subset of all of the features described,or a particular embodiment may include all of the features described.

The leading digit(s) of reference numbers appearing in the Figuresgenerally corresponds to the Figure number in which that component isfirst introduced, such that the same reference number is used throughoutto refer to an identical component which appears in multiple Figures.Signals and connections may be referred to by the same reference numberor label, and the actual meaning will be clear from its use in thecontext of the description.

As used herein, the term “substrate” means a material upon which aprocess is conducted and substrates include silicon, sapphire, or othersuitable materials.

As used herein, the term “template” means one or more layers that form abase suitable for epitaxial growth, and templates include silicon,sapphire, GaN/silicon, GaN/sapphire, GaN/Aluminum Nitride (AlN),GaN/Hafnium Nitride (HfN), GaN/Zirconium Nitride (ZrN), or any othersuitable materials, structures, pattern templates, or substrates.

As used herein, physical vapor deposition (“PVD”) describes depositionmethods that can be used to produce thin films and coatings, and PVDincludes cathode arc deposition, electron-beam PVD, evaporativedeposition, pulsed-laser deposition, and sputtering.

As used herein, “sputtering” includes one or more of the following:direct current (DC) sputtering, radio frequency (RF) sputtering,reactive sputtering, and magnetron sputtering.

It is noted that many processes and methods described herein make use ofnumbered/lettered steps. These processes and methods can be performed inthe order established by the numbers/letters, but the specification ofthe present invention also contemplates performing these processes andmethods in any other suitable order. Moreover, the specification alsocontemplates performing the corresponding processes and methods with anyone or more of the described steps such that a given step or steps couldbe optionally omitted and/or an additional step or steps could beoptionally added.

FIG. 1 is a flowchart of a method 101 for growing gallium-nitride(GaN)-based devices. In some embodiments, the method of flowchart 101 isperformed within a single deposition chamber. In other embodiments,method 101 is performed in a plurality of separate deposition chambers.In some embodiments, method 101 includes any one or more of blocks105-110 (for example, in some embodiments, blocks 106 and 108 areoptional). In some embodiments, at block 105, a substrate (e.g.,sapphire or silicon) is positioned for subsequent deposition. In someembodiments, at block 106, substrate conditioning is performed. In someembodiments, at block 107, aluminum nitride (AlN) is sputtered onto thesubstrate, where X represents the thickness of the sputtered AlN. Insome embodiments, at block 108, AlN conditioning is performed (e.g., insome embodiments, oxide removal). In some embodiments, at block 109, GaNis sputtered, where Y represents the thickness of the sputtered GaN. Insome such embodiments, the GaN sputtering includes doping (e.g., dopingwith silicon, magnesium, iron, carbon, or the like) and/or increasedadatom mobility. In some embodiments, at block 110, GaN is sputtered,wherein Z represents the thickness of the sputtered GaN. In some suchembodiments, the GaN sputtering includes doping (e.g., doping withsilicon, magnesium, iron, carbon, or the like) and/or increased adatommobility (sometimes referred to herein as EALS). In some embodiments,the GaN is alloyed with scandium, zirconium, hafnium, indium, aluminum,or any other suitable element.

FIG. 2 is a schematic diagram of a system 201 for growing GaN-baseddevices. In some embodiments, system 201 is used to perform the methodof flowchart 101 shown in FIG. 1. In some embodiments, system 201includes a load lock 205 where substrate wafers 298 are loaded into andfinished wafers 299 are removed from system 201. In some embodiments,system 201 includes a substrate-conditioning module 206 (e.g., a modulefor performing block 106 of FIG. 1), an AlN-deposition module 207 (e.g.,a module for performing block 107 of FIG. 1), an AlN-conditioning module208 (e.g., a module for performing block 108 of FIG. 1), aGaN-deposition module 209 (e.g., a module for performing block 109 ofFIG. 1), and a doping module 210 for doped GaN deposition. In someembodiments, modules 205-210 are contained within a single depositionchamber. In other embodiments, each of modules 205-210 is a depositionchamber. In some embodiments, system 201 includes a wafer-handling robot215 for moving the wafer from module to module within system 201.

FIG. 3 is a schematic diagram of a GaN structure 301. In someembodiments, GaN structure 301 is produced using system 201 of FIG. 2and/or method 101 of FIG. 1. In some embodiments, GaN structure 301includes a substrate layer 305, a sputtered aluminum nitride (AlN) layer306 on substrate layer 305 (in some such embodiments, the thickness ofAlN layer 306=X), a sputtered GaN layer 307 on AlN layer 306 where thethickness of GaN layer 307=Y (in some such embodiments, GaN layer 307 isdoped (e.g., doped with silicon, magnesium, or the like)), and asputtered GaN layer 308 on GaN layer 307 where the thickness of GaNlayer 308=Z (in some such embodiments, GaN layer 308 is doped (e.g.,doped with silicon, magnesium, or the like)).

Conventional industry systems produce GaN-based devices usingmetal-organic chemical vapor deposition (MOCVD) for the growth of theGaN. In some embodiments, the present invention substitutes conventionalMOCVD GaN processes with sputtered GaN, which allows for: lower waferbow and thus better wafer/device uniformity due to the sputtering, lowerprocess temperature, and less costly chemical usage of NH₃ and Ga(CH₃)₃and the like. In some embodiments, sputtering processes are more simplyemployed and less costly than MBE processes due to less complexequipment requirements.

FIG. 4 is a schematic diagram of a low-temperature group IIIA-nitridesputtering system 401. In some embodiments, sputtering system 401includes a vacuum chamber 405. In some embodiments, chamber 405 includesa wafer holder 406 and a sputtering gun 407 (e.g., in some embodiments,sputtering gun 407 is a gallium sputtering gun and includes a galliumtarget). In some embodiments, sputtering gun 407 includes metal gasketsand other suitable components such that it is suitable to operate in lowtemperatures (e.g., below zero degrees Celsius). In some embodiments,system 401 includes a cooling system 408 that cools the gallium targetof sputtering gun 407 such that the gallium target is maintained in asolid state during sputtering. In some embodiments, cooling system 408is operatively coupled to sputtering gun 407 via cold-input line 409 andheat-output line 410. In some embodiments, cooling system 408 circulatesone or more heat-transfer fluids through lines 409 and 410 to maintainthe gallium target in a solid state during sputtering (e.g., in somesuch embodiments, the heat-transfer fluid is a cryogenic fluid such asliquid nitrogen and/or liquid hydrogen (in some embodiments, liquidnitrogen and/or liquid hydrogen is used when sputtering system 401 isused with large wafer and/or wafer platter production systems), one ormore alcohols, or other suitable heat-transfer fluids). In someembodiments, system 401 includes a voltage supply 415 that is connectedto system 401 via wires 499. In some embodiments, voltage is increasedby voltage supply 415 as wafer-size increases. In some embodiments,system 401 includes an optical path 420 for in situ closed or openprocess monitoring (in some such embodiments, path 420 is operativelycoupled to a pyrometer and/or an optical reflectivity system that iscomputer corrected for emissivity).

In some embodiments, the GaN growth processes/systems described hereinare complementary to epitaxial atomic layer sputtering (EALS). In someembodiments, EALS is a process that results in effectivelystoichiometric epitaxial growth of a metal-nitride compound materialupon a substrate using sputtering or reactive sputtering where the ratioof the metal (e.g., gallium) to active nitrogen (N) atoms arriving atthe surface of the metal nitride being formed is periodically variedbetween metal-rich to N-rich conditions as compared to thestoichiometric composition of the metal-nitride compound. In someembodiments, this process of switching from metal-rich conditions tometal-lean conditions is accomplished by (1) reducing the metal flux tothe surface of the metal nitride being formed, or (2) increasing theactive nitrogen flux, or (3) increasing the temperature of the substrate(or exposing the surface of the metal nitride being formed) to increaseevaporation rate (i.e., lower the residence time) of the metal adatoms,or any combination of (1)-(3). In some embodiments, the metal-richconditions increase the mobility of adatom by reducing the effect ofunsatisfied (or dangling) bonds at the surface to enhance surfacemigration, which results in non-columnar step growth and thushigher-quality and smoother films. In general, in some embodiments,increased surface migration of adatoms improves crystal quality of thedeposited materials by assisting the adatoms to incorporate inlow-energy sites on the growth front. Similarly, in some embodiments,increasing the surface temperature or applying low-energy ions canincrease surface migration of adatoms to improve thin film quality.Accordingly, in some embodiments, the present invention provides EALS.In some embodiments, this process includes using a separate nitrogenplasma source (e.g., a radio frequency (RF) nitrogen source) or even ionbeam-assisted deposition.

FIG. 5A is a schematic diagram that illustrates a plurality 501 ofdifferent epitaxial growth modes according to some embodiments of thepresent invention. In epitaxial film growth, deposited material(s)ideally form ordered crystals with atomic arrangement and orientationthat are determined by the crystallographic structure of the substrate505. In some embodiments, depending on the surface mobility of arrivingatoms and the properties of the substrate and epitaxial film, differentgrowth modes 510, 520, and/or 530 are obtained. In some embodiments,depending on the surface mobility of the arriving atoms on the substratesurface, and other factors such as average terrace length of surfacesteps, crystal orientation and defect density of substrate, surface andinterface energetic, lattice mismatch between film and substrate, theepitaxial growth process 1) starts and progresses in one of the abovemodes, 2) is a mixture of two or more modes, or 3) starts in one modeand then transitions to another mode or a mixed growth mode.

In some embodiments, growth mode 510 (represented by the progressionfrom 510 a to 510 b) is referred to as two-dimensional (2D) islandgrowth. In some embodiments, in mode 510, small islands nucleate overthe surface and laterally grow to coalesce into a layer, resulting inmany grain boundaries. In some embodiments, growth mode 520 (representedby the progression from 520 a to 520 b) is referred to asthree-dimensional (3D) island growth. In some embodiments, in mode 520,small islands nucleate over the surface and grow while more islands areformed on top of earlier islands before the bottom layers are completed,resulting in increased surface roughness (in some embodiments, mode 520includes columnar growth). In some embodiments, growth mode 530(represented by the progression from 530 a to 530 b) is referred to asstep-flow growth. In some embodiments, in mode 530, atoms arriving onthe surface migrate and incorporate at step edges to complete layers bystep flow (in some embodiments, mode 530 occurs when the surfacediffusion is large compared to average terrace length).

FIG. 5B is a set 502 of atomic-force microscopy (AFM) images of GaNgrowth. Image 540 shows the smooth GaN with Ga droplets that occurs insome embodiments where Ga-rich growth conditions are in place. In someembodiments, epitaxial atomic layer sputtering (EALS) is implementedduring the growth of the GaN such that there is a modulation between theGa-rich growth conditions shown in image 540 and nitrogen-rich growthconditions. Image 545 shows the atomic steps of the smooth GaN with noGa droplets that are present in the final state of the GaN film (afterthe modulations between the Ga-rich conditions and the nitrogen-richconditions), prior to subsequent deposition. In some embodiments, theroot-mean-squared (RMS) roughness of image 540 is about 8 Angstroms. Insome embodiments, the RMS roughness of image 545 is about 2 Angstroms.

In some embodiments, the present invention generates a material thatincludes GaN on two-dimensional (2D) photonic crystal using one or moreof the processes described herein. In some embodiments, the GaN on 2Dphotonic crystal includes repeating periods of air/GaN, which arelocated on a layer of GaN, which is (optionally) located on a layer ofAlN, which is located on sapphire. In some embodiments, the GaN on 2Dphotonic crystal includes repeating periods of air/GaN, which arelocated on a layer of GaN, which is (optionally) located on a layer ofAlN, which is located on HfN. In some embodiments, the GaN on 2Dphotonic crystal includes repeating periods of air/GaN, which arelocated on a layer of GaN, which is (optionally) located on a layer ofAlN, which is located on ZrN. In some embodiments, the GaN on 2Dphotonic crystal includes repeating periods of air/GaN, which arelocated on a layer of GaN, which is (optionally) located on a layer ofAlN, which is located on any other suitable Group IIIA nitride. In someembodiments, any of the GaN structures are replaced by HfGaN. In someembodiments, any of the GaN structures are replaced by ZrGaN.

In some embodiments, the resulting material thickness of the air isrepresented as: thickness of air void (T_(air))=(wavelength)*(1−2M)/4,where M=Integer (0,1,2,3,4,5 . . . ).

In some embodiments, the resulting material thickness of GaN between theair and sapphire (Al₂O₃) is represented as: thickness of GaN between airand Al₂O₃ (TGaN)=(wavelength)*(1−2M)/(4n), where M is an integer (e.g.,0,1,2,3,4,5 . . . ) and n is the index of refraction.

In some embodiments, the GaN on 2D photonic crystal includes effectivelyno carbon compared to GaN formed by MOCVD. In some embodiments, the GaNon 2D photonic crystal includes effectively no hydrogen compared to GaNformed by MOCVD.

In some embodiments, the GaN on 2D photonic crystal includes effectivelylarger epitaxial grains or epi-islands as compared to GaN formed byMOCVD and/or MBE. In some embodiments, the GaN on 2D photonic crystalincludes epitaxial films with a substantially non-columnar structure. Insome embodiments, the GaN on 2D photonic crystal includes ultra-smoothsurfaces due to improved 2D growth. In some embodiments, the GaN on 2Dphotonic crystal includes quantum wells that are smoother than GaNformed by conventional processes. In some embodiments, thinner GaNthickness is required for dislocation self-annihilation and/ordislocation bending, as compared to conventional methods of GaN growth.In some embodiments, low-temperature sputtered GaN on any material,template, or substrate has significantly different density of misfitdislocations than high-temperature growth of GaN. In some embodiments,the GaN on 2D photonic crystal includes point-defect density that issubstantially different than GaN formed by conventional processes. Insome embodiments, the GaN on 2D photonic crystal includes lower waferbow than GaN formed by conventional methods. In some embodiments, theGaN on 2D photonic crystal includes substantially different stresslevels in films, as compared to GaN formed by conventional methods. Insome such embodiments, the film stress levels are detectable by Ramanspectroscopy.

In some embodiments, subsequent epitaxial growth of the GaN materials ofthe present invention results in any suitable light emitting, lightdetecting, light harvesting, or transistor devices (includingtransistors with vertical carrier flow). In some embodiments, the GaNmaterials of the present invention are used with GaN-based displays(e.g., cell phones, tablets, and the like), GaN-based solar cells,GaN-based detector arrays, GaN-based very large scale integrationapplications, GaN coatings for windows, a GaN-based high temperatureindium tin oxide (ITO) replacement, and the like. In some embodiments,wafers of the GaN materials of the present invention have a diameterthat is approximately six inches or less. In some embodiments, wafers ofthe GaN materials of the present invention have a diameter that islarger than approximately six inches.

In some embodiments, the present invention provides a magnetron reactivesputtering system for making the GaN materials of the present invention.In some embodiments, other suitable sputtering techniques are used suchas direct current (DC) or radio frequency (RF) sputtering. In someembodiments, the system for making the GaN materials of the presentinvention includes a nitrogen plasma source or an ion gun. In someembodiments, a gallium target in a solid state is used and EALSprocesses are implemented to make the GaN materials of the presentinvention. In some such embodiments, the solid-state gallium allows forsputter up, sputter down, or sputter sideways configurations.

In some embodiments, the present invention provides a sputter GaN growthprocess that uses a solid gallium source that is located in closeproximity (e.g., less than about 8 inches) to the heated substrate. Insome embodiments, the solid gallium source is located further away fromthe substrate. In some embodiments, the wafer substrate is heated to arange of 1100-1000 degrees Celsius (C), in some embodiments, a range of1000-900 degrees C., in some embodiments, a range of 900-800 degrees C.,in some embodiments, a range of 800-700 degrees C., in some embodiments,a range of 700-600 degrees C., in some embodiments, a range of 600-500degrees C., in some embodiments, a range of 500-400 degrees C., and, insome embodiments, a range of 400 degrees C. down to room temperature.

In some embodiments, the proximity and type of sputtering gun (e.g.,balanced, unbalanced, and partially balanced) allow the process toachieve desired add-atom energy due to the sputter gun's plasmainteraction while minimizing damage to the GaN film. In someembodiments, the ionization brought about by the close proximity of thesource and the type of sputtering gun allows for dislocation bendingand/or self-annihilation.

In some embodiments, the sputtering gun used for the processes of thepresent invention is manufactured with all-metal gasket seals and/or thetemperatures of the N₂ used with the sputtering gun are kept at or belowthe melting point of gallium so that the gallium can be made solid. Insome embodiments, heat-transfer liquids such as various alcohols areused. In some embodiments, the characteristic dimension of thesputtering target is larger than 2 inches in diameter with such acooling system.

In some embodiments, there are advantages for a gallium gun toincorporate a rotating magnet sputtering gun. In some embodiments, thereare other advantages of using ringed sputtering targets and/or multiplering sputtering targets for co-deposition of compound materials likeindium gallium nitride (InGaN) and/or aluminum gallium nitride (AlGaN).In some embodiments, hafnium, zirconium, or silicon are included assputtering targets. In some embodiments, dilute SiH₄ in nitrogen issupplied and the gas-delivery system contains a double-dilution system.In some embodiments, a ringed sputtering target allows for in situreflectivity measurements. In some embodiments, radio frequency ordirect current processes are both applicable. In some embodiments, whenEALS is used, varying between gallium-rich and gallium-lean conditionsis accomplished by varying the temperature, the pressure, the argon, thenitrogen, the gallium source power, the growth rate, or any othersuitable variable.

In some embodiments, the present invention provides a magnetronsputtering epitaxial process that includes any one or more of thefollowing steps: (1) providing any combination of substrate thatincludes any number and/or size wafer substrate(s) or wafer substratecassettes that enter a load lock, (2) wherein the substrate is silicon,sapphire, GaN/sapphire, AlN/sapphire, GaN/silicon, AlN/silicon or anyother suitable template such as any other Group IIIA nitride on sapphireor silicon, (3) transferring the wafer substrate to an epitaxial chambervia any suitable method or mechanism of manual or robotic transfer, (4)placing the wafer substrate into an AlN epitaxial sputtering (or otherPVD), MOCVD, or MBE chamber where AlN is grown to any thickness(columnar or non-columnar) on the wafer substrate, (5) transferring theAlN/wafer substrate via any suitable method or mechanism of manual orrobotic transfer, (6) placing the AlN/substrate wafer into a GaNepitaxial sputtering chamber where GaN is grown to any thickness viasputtering upon the AlN/wafer substrate (in some embodiments, duringthis step, the gallium is in a solid state and EALS processes areimplemented, and, in some embodiments, optional silicon (Si), hafnium(Hf), and/or zirconium (Zr) doping is included in the process), (7)transferring the sputtered GaN/AlN/wafer substrate via any suitablemethod or mechanism of manual or robotic transfer, (8) placing thesputtered GaN/AlN/wafer substrate into a Grown-Epitaxial Metal Mirror(GEMM) sputtering chamber where GEMM growth occurs via sputtering uponthe sputtered GaN/AlN/wafer substrate (in some such embodiments, theGEMM growth is performed according to the descriptions in U.S. Pat. Nos.7,915,624, 8,253,157, and/or 8,890,183, which were introduced above andincorporated herein by reference); in some embodiments, the processrepeats steps 5,6,7 in any order or combination as required, (9)optionally growing a layer of AlN to any suitable thickness viasputtering upon the GEMM, (10) transferring the sputteredGEMM/GaN/AlN/wafer substrate via any suitable method or mechanism ofmanual or robotic transfer, (11) capping the sputteredGEMM/GaN/AlN/substrate by a final layer of sputtered GaN grown to anysuitable thickness via sputtering, (12) transferring the sputteredGaN/GEMM/GaN/AlN/wafer substrate via any suitable method or mechanism ofmanual or robotic transfer, and (13) placing the sputteredGaN/GEMM/GaN/AlN/wafer substrate into an MOCVD, MBE, or sputtering (orother PVD) system for the growth of quantum well or quantum wells (alsoknown as the active region) and a P-type layer or P-type layers.

In some embodiments, the present invention provides an epitaxialmaterials growth process that includes any one or more of the followingsteps: (1) providing any combination of substrate that includes anynumber and/or size wafer substrate(s) or wafer substrate cassettes thatenter a load lock, (2) wherein the substrate is silicon, sapphire,GaN/sapphire, AlN/sapphire, GaN/silicon, AlN/silicon or any othersuitable template such as any other Group IIIA nitride on sapphire orsilicon, (3) transferring the wafer substrate to an epitaxial chambervia any suitable method or mechanism of manual or robotic transfer, (4)placing the wafer substrate into an AlN epitaxial sputtering (or otherPVD), MOCVD, or MBE chamber where AlN is grown to any thickness(columnar or non-columnar) on the wafer substrate, (5) transferring theAlN/wafer substrate via any suitable method or mechanism of manual orrobotic transfer, (6) placing the AlN/substrate wafer into aGrown-Epitaxial Metal Mirror (GEMM) sputter chamber where GEMM growthoccurs via sputtering upon the AlN/wafer substrate (in some suchembodiments, the GEMM growth is performed according to the descriptionsin U.S. Pat. Nos. 7,915,624, 8,253,157, and/or 8,890,183, which wereintroduced above and incorporated herein by reference); in someembodiments, the process repeats steps 1-6 in any order or combinationas required, (7) growing a layer of AlN to any suitable thickness viasputtering upon the GEMM, (8) transferring the sputtered GEMM/AlN/wafersubstrate via any suitable method or mechanism of manual or robotictransfer, (9) capping the sputtered GEMM/AlN/wafer substrate by a finallayer of sputtered GaN grown to any suitable thickness via sputteringupon the GEMM/AlN/wafer substrate (in some such embodiments, the galliumis in a solid state and EALS processes are implemented, and, in someembodiments, Si, Hf, Zr doping occurs), (10) transferring the sputteredGaN/GEMM/AlN/wafer substrate via any suitable method or mechanism ofmanual or robotic transfer, and (11) placing the sputteredGaN/GEMM/AlN/wafer substrate into an MOCVD, MBE, or sputtering (or otherPVD) system for the growth of quantum well or quantum wells (also knownas the active region) and a P-type layer or P-type layers.

In some embodiments, the present invention provides an epitaxialmaterials growth process that includes any one or more of the followingsteps: (1) providing any combination of substrate that includes anynumber and/or size wafer substrate(s) or wafer substrate cassettes thatenter a load lock, (2) wherein the substrate is silicon, sapphire,GaN/sapphire, AlN/sapphire, GaN/silicon, AlN/silicon or any othersuitable template such as any other Group IIIA nitride on sapphire orsilicon, (3) transferring the wafer substrate to an epitaxial chambervia any suitable method or mechanism of manual or robotic transfer, (4)placing the wafer substrate into a Grown-Epitaxial Metal Mirror (GEMM)sputtering chamber where GEMM growth occurs via sputtering upon thewafer substrate (in some such embodiments, the GEMM growth is performedaccording to the descriptions in U.S. Pat. Nos. 7,915,624, 8,253,157,and/or 8,890,183, which were introduced above and incorporated herein byreference), (5) transferring the GEMM/wafer substrate to an epitaxialchamber via any suitable method or mechanism of manual or robotictransfer, (6) placing the GEMM/wafer substrate into an AlN epitaxialsputtering chamber where AlN is grown to any suitable thickness(columnar or non-columnar); in some embodiments, the process repeatssteps 4 and 5 as required, (7) optionally growing a layer of AlN to anysuitable thickness via sputtering upon the GEMM, (8) transferring thesputtered GEMM/ALN/GEMM wafer substrate via any suitable method ormechanism of manual or robotic transfer, (9) capping the sputteredGEMM/ALN/GEMM/wafer substrate by a final layer of sputtered GaN grown toany suitable thickness via sputtering upon the GEMM/ALN/GEMM/wafersubstrate (in some such embodiments, the gallium target used during thesputtering is in a solid state and EALS processes are implemented, and,in some embodiments, Si, Hf, Zr doping occurs), (10) transferring thesputtered GaN/GEMM/ALN/GEMM/wafer substrate via any suitable method ormechanism of manual or robotic transfer, and (11) placing the sputteredGaN/GEMM/ALN/GEMM/wafer substrate into an MOCVD, MBE, or sputtering (orother PVD) system for the growth of quantum well or quantum wells (alsoknown as the active region) and a P-type layer or P-type layers.

In some embodiments, the present invention provides an epitaxialmaterials growth process that includes any one or more of the followingsteps: (1) providing any combination of substrate that includes anynumber and/or size wafer substrate(s) or wafer substrate cassettes thatenter a load lock, (2) wherein the substrate is silicon, sapphire,GaN/sapphire, AlN/sapphire, GaN/silicon, AlN/silicon or any othersuitable template such as any other Group IIIA nitride on sapphire orsilicon, (3) transferring the wafer substrate to a sputtering epitaxialchamber via any suitable method or mechanism of manual or robotictransfer, (4) growing any Group IIIA nitride material to any suitablethickness (columnar or non-columnar) on the wafer substrate, (5)transferring the Group IIIA nitride/wafer substrate via any suitablemethod or mechanism of manual or robotic transfer, (6) placing the GroupIIIA nitride/wafer substrate into a GEMM sputtering chamber where GEMMgrowth occurs via sputtering upon the Group IIIA nitride/wafer substrate(in some such embodiments, the GEMM growth is performed according to thedescriptions in U.S. Pat. Nos. 7,915,624, 8,253,157, and/or 8,890,183,which were introduced above and incorporated herein by reference); insome embodiments, the process repeats in any order or combination asrequired, (7) optionally growing a layer of AlN or any other Group IIIAnitride to any suitable thickness via sputtering upon the GEMM, (8)transferring the sputtered GEMM/Group IIIA nitride/wafer substrate viaany suitable method or mechanism of manual or robotic transfer, (9)capping the sputtered GEMM/Group IIIA nitride/wafer substrate by a finallayer of sputtered GaN grown to any suitable thickness via sputteringupon the GEMM/Group IIIA nitride/wafer substrate (in some suchembodiments, the gallium is in a frozen/solid state and EALS processesare implemented, and, in some embodiments, Si, Hf, Zr doping isimplemented), (10) transferring the sputtered GaN/GEMM/Group IIIAnitride/wafer substrate via any suitable method or mechanism of manualor robotic transfer, and (11) placing the sputtered GaN/GEMM/Group IIIAnitride/wafer substrate into a MOCVD, MBE, or sputtering (or other PVD)system for the growth of quantum well or quantum wells (also known asthe active region) and a P-type layer or P-type layers.

In some embodiments, the Group IIIA nitride is replaced by any otherGroup IIIA nitride, or any combination of Group IIIA nitride layersand/or compounds. In addition, in some embodiments, these materialsinclude silicon (Si), Hf, Zr, and/or magnesium (Mg). In someembodiments, a wafer(s) and/or substrate(s) is inserted, moved orotherwise directly transferred via any suitable method or mechanism(manual or robotic) within or between any combination and/or any numberof materials-specific or process-specific epitaxial sputtering (or otherPVD), MOCVD, or MBE chambers or equipment. In some embodiments, theprocesses of the present invention occur in materials-specificsputtering (or other PVD), MOCVD, or MBE epitaxial chamber(s) and/orwith any combination of optional wafer transfer(s) within and betweenmaterials-specific sputtering (or other PVD), MOCVD or MBE chamber(s).In some embodiments, the processes of the present invention occur in amaterials-specific sputtering (or other PVD), MOCVD or MBE epitaxialchamber(s) with no wafer transfer(s).

Growing gallium nitride (GaN) films by conventional sputteringtechniques is typically considered not useful due to the film qualitybeing poor (e.g., GaN films grown by conventional sputtering techniquesgenerally have a characteristic X-ray diffraction (XRD) rocking curvefull width at half maximum value of 620 arcseconds and/or greater).Since these sputtered epitaxial grown films are considered lower qualitythan what can be produced by MOCVD or MBE methods, conventionalsputtered epitaxial growth techniques have not been designed withintentional doping.

In some embodiments, the present invention provides N-type doping GaNwith a background electron concentration of about 5×10¹⁶/cm³ (also knownunintentionally doped) that is intentionally doped with a doping elementsuch as silicon (or titanium (Ti), zirconium (Zr), hafnium (Hf), oxygen(O), sulfur (S), selenium (Se) and/or tellurium (Te)) to achieve anelectron concentration of greater than 5×10¹⁶/cm³ such as 1×10¹⁸/cm³ to5×10²⁰/cm³ or higher. In some embodiments, these intentionally dopedmaterials' electron concentrations are used for making ohmic contactsand used as a conductive material.

In some embodiments, the present invention provides a method for growinghigh quality GaN by sputtering with optional n-type doping that includesany one or more of the following: (1) out-gassing the wafer, chamber andwafer holder, (2) GaN nucleation, wherein the GaN nucleation includes(a) setting the temperature to allow sufficient adatom energy so thatadatoms are able to find an energetically favorable place in the surfaceof the template to create initial epitaxial growth, (b) setting thechamber vacuum pressure to allow the formation of a plasma, (c)supplying plasma gas to the chamber, (d) supplying nitrogen gas to thechamber, and (e) providing power to the gun of solid gallium (Ga) targetto provide gallium and to allow sufficient adatom energy so that adatomsare able to find an energetically favorable place in the surface of thetemplate to create initial epitaxial growth, wherein the method furtherincludes (3) once nucleation is reached with minimal thickness, shuttingoff the plasma gas source, (4) growing GaN with appropriate temperaturesand gas flows and Ga gun target power to allow for best GaN growth uponGaN layers, wherein the GaN sputtering includes doping, and the dopingincludes (a) co-sputtering of dopant, (b) thermal evaporation of dopant,(c) e-beam evaporation of dopant, (d) Ga mixture with dopant insputtering gun, (e) gas injection of dopant reactant including examplesof dilute SiH₄, Si₂H₆, tetraethylsilane, and/or other reactants holdingdopant (Si) in a carrier gas (H₂, N₂, Ar, Xe, He, Kr, Rn, and the like),and (f) ion implantation doping of silicon, wherein the method furtherincludes (5) ramping temperature to high enough temperature to removeany potential gallium droplets and letting sit until the galliumdroplets are gone, and (6) turning off any of the above-mentionedvariables as needed to remove the wafer.

The GaN industry is concerned with both the X-ray diffraction (XRD) 002(symmetric) and 102 (asymmetric) peak full-width half-maximum (FWHM)values of Omega rocking curves for determination of quality for theirresulting devices. In some embodiments, the present invention provides asputtering GaN process that enables both 002 and 102 peak FWHM values tobe under 1000 arcseconds, and in some embodiments, below 600 arcseconds,and in some embodiments, below 300 arcseconds, and in some embodiments,below 200 arcseconds, and in some embodiments, below 100 arcseconds. Insome embodiments of the invention, the 002 peak FWHM is below 500arcseconds and the 102 peak FWHM is below 1000 arcseconds.

In some embodiments of the invention, the 002 peak FWHM is below 400arcseconds and the 102 peak FWHM is below 800 arcseconds. In someembodiments, the 002 peak FWHM is below 300 arcseconds and the 102 peakFWHM is below 600 arcseconds. In some embodiments, the 002 peak FWHM isbelow 300 arcseconds and the 102 peak FWHM is below 500 arcseconds. Insome embodiments, the 002 peak FWHM is below 300 arcseconds and the 102peak FWHM is below 400 arcseconds. In some embodiments, the 002 peakFWHM is below 250 arcseconds and the 102 peak FWHM is below 350arcseconds.

In some embodiments, the present invention provides a method thatincludes growing gallium nitride (GaN) via physical vapor deposition(PVD) (e.g., via sputtering) such that the grown GaN has an Omegarocking curve full-width half-maximum (FWHM) X-ray diffractionmeasurement for both 002 and 102 peaks that is less than 1000arcseconds.

In some embodiments, the present invention provides: (1) co-sputteringany of Si, Ti, Zr, Hf, O, S, Se and/or Te while growing GaN viasputtering, (2) thermal evaporation of Si, Ti, Zr, Hf, O, S, Se and/orTe while growing GaN via sputtering, (3) e-beam evaporation is of Si,Ti, Zr, Hf, O, S, Se and/or Te while growing GaN via sputtering, (4) Gamixture with Si, Ti, Zr, Hf, O, S, Se and/or Te to grow n-type GaN, (5)gas injection of dilute SiH₄, GeH₄, Si₂H₆, tetraethylsilane, and/orother reactants holding the already mentioned elements in carrier gas(H₂, N₂, Ar, Xe, He, Kr, Rn . . . ) while growing GaN via sputtering,and (6) ion implantation doping of Si, Ti, Zr, Hf, O, S, Se and/or Tewhile growing GaN via sputtering. In some embodiments, the presentinvention further includes (7) other group IV element doping (e.g., insome embodiments, Ge or Sn), (8) co-doping any combination of the aboveelements, (9) Surfactant (e.g., In) enhanced n-doping, (10) modulateddoping to create special doping profile or internal electric fields,and/or (11) delta doping any of the above-mentioned elements. In someembodiments, the present invention includes applications of surfactantsfor modifying or enhancing growth.

In some embodiments, the GaN grown using the methods described hereinhas an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement (for the 002 peak and/or the 102 peak) of 0-5arcseconds; in some embodiments, a FWHM of 5-10 arcseconds; in someembodiments, a FWHM of 10-15 arcseconds; in some embodiments, a FWHM of15-20 arcseconds; in some embodiments, a FWHM of 20-25 arcseconds; insome embodiments, a FWHM of 25-30 arcseconds; in some embodiments, aFWHM of 30-40 arcseconds; in some embodiments, a FWHM of 40-50arcseconds; in some embodiments, a FWHM of 50-100 arcseconds; in someembodiments, a FWHM of 100-150 arcseconds; in some embodiments, a FWHMof 150-200 arcseconds; in some embodiments, a FWHM of 200-250arcseconds; in some embodiments, a FWHM of 250-300 arcseconds; in someembodiments, a FWHM of 300-400 arcseconds; in some embodiments, a FWHMof 400-500 arcseconds; in some embodiments, a FWHM of 500-600arcseconds; in some embodiments, a FWHM less than 620 arcseconds; insome embodiments, a FWHM of less than 600 arcseconds; in someembodiments, a FWHM of less than 500 arcseconds; in some embodiments, aFWHM of less than 400 arcseconds; in some embodiments, a FWHM of lessthan 300 arcseconds; in some embodiments, a FWHM of less than 240arcseconds; in some embodiments, a FWHM of less than 200 arcseconds; insome embodiments, a FWHM of less than 100 arcseconds; in someembodiments, a FWHM of less than 50 arcseconds; in some embodiments, aFWHM of less than 40 arcseconds; in some embodiments, a FWHM of lessthan 30 arcseconds; in some embodiments, a FWHM of less than 27arcseconds; in some embodiments, a FWHM of less than 25 arcseconds; insome embodiments, a FWHM of less than 20 arcseconds; in someembodiments, a FWHM of less than 10 arcseconds, and in some embodiments,a FWHM of less than 5 arcseconds.

In some embodiments, the present invention provides a method thatincludes growing gallium nitride (GaN) via physical vapor deposition(PVD) (e.g., via sputtering) such that the grown GaN has an Omegarocking curve full-width half-maximum (FWHM) X-ray diffractionmeasurement of less than 620 arcseconds. In some embodiments, the grownGaN has an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement of less than 1000 arcseconds. In someembodiments, the method further includes during the PVD of the GaN,doping the GaN by co-sputtering at least one dopant selected from thegroup consisting of: silicon (Si), titanium (Ti), zirconium (Zr),hafnium (Hf), oxygen (O), sulfur (S), selenium (Se), and tellurium (Te).In some embodiments, the method further includes during the PVD of theGaN, doping the GaN by thermally evaporating at least one selected fromthe group consisting of: Si, Ti, Zr, Hf, O, S, Se, and Te. In someembodiments, the method further includes during the PVD of the GaN,doping the GaN by e-beam evaporating at least one selected from thegroup consisting of: Si, Ti, Zr, Hf, O, S, Se, and Te.

In some embodiments of the method, the growing of the GaN includesdoping the GaN to form an n-type GaN using a mixture of Ga and at leastone selected from the group consisting of: Si, Ti, Zr, Hf, O, S, Se, andTe. In some embodiments, the method further includes during the PVD ofthe GaN, doping the GaN by: gas injecting at least one selected from thegroup consisting of dilute: SiH₄, GeH₄, Si₂H₆, tetraethylsilane, and/orother reactants; and holding in a carrier gas (H₂, N₂, Ar, Xe, He, Kr,Rn, or the like) and gas injecting at least one selected from the groupconsisting of: Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments,the method further includes during the PVD of the GaN, doping the GaN byion-implantation doping at least one selected from the group consistingof: Si, Ti, Zr, Hf, O, S, Se, and Te.

In some embodiments of the method, the doping of the GaN uses at leastone dopant selected from the group consisting of germanium (Ge) and tin(Sn) instead of, or in addition to, the previously recited elements. Insome embodiments, the doping of the GaN includes surfactant-enhanced(e.g., In) n-doping. In some embodiments, the doping of the GaN includesmodulated doping to create a special doping profile or internal electricfield. In some embodiments, the doping of the GaN includes delta dopingany of the previously recited elements.

In some embodiments, the present invention provides a method thatincludes growing gallium nitride (GaN) via physical vapor deposition(PVD) (e.g., in some embodiments, via sputtering) such that the grownGaN has an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement (in the 002 plane and/or the 102 plane) of lessthan 25 arcseconds.

In some embodiments, the present invention provides a method thatincludes growing gallium nitride (GaN) via physical vapor deposition(PVD) (e.g., in some embodiments, via sputtering) such that the grownGaN has an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement for both 002 and 102 peaks that is less than1000 arcseconds.

In some embodiments, the present invention provides a method thatincludes sputtering epitaxial GaN; and intentional n-type doping duringthe sputtering. In some embodiments of the method, the doping includesco-sputtering silicon (Si). In some embodiments, the doping includesthermal evaporation of Si. In some embodiments, the doping includese-beam evaporation of Si. In some embodiments, the sputtering includesusing a target material that includes a mixture of Ga and Si. In someembodiments, the doping includes gas injecting SiH₄, Si₂H₆,tetraethylsilane, and/or other reactants (in some embodiments, in diluteportions) with a carrier gas (e.g., H₂, N₂, Ar, Xe, He, Kr, Rn, and thelike) holding Si.

In some embodiments, the doping includes ion-implantation doping of Si.In some embodiments, the doping includes sputtering at least oneselected from the group consisting of silicon (Si), titanium (Ti),zirconium (Zr), hafnium (Hf), oxygen (O), sulfur (S), selenium (Se), andtellurium (Te). In some embodiments, the doping includes thermalevaporation of at least one selected from the group consisting of Si,Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping includese-beam evaporation of at least one selected from the group consisting ofSi, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the sputteringincludes using a target material that includes a mixture of Ga and atleast one selected from the group consisting of Si, Ti, Zr, Hf, O, S,Se, and Te. In some embodiments, the doping includes gas injecting SiH₄,Si₂H₆, tetraethylsilane, and/or other reactants with a carrier gas(e.g., H₂, N₂, Ar, Xe, He, Kr, Rn, and the like) holding at least oneselected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te.

In some embodiments, the doping includes ion-implantation doping of atleast one dopant selected from the group consisting of Si, Ti, Zr, Hf,O, S, Se, and Te. In some embodiments, the doping includes modulateddoping using at least one dopant selected from the group consisting ofSi, Ti, Zr, Hf, O, S, Se, and Te to create a special doping profile orinternal electric fields. In some embodiments, the doping includes deltadoping at least one dopant selected from the group consisting of Si, Ti,Zr, Hf, O, S, Se, and Te. In some embodiments, the doping includesco-doping at least one dopant selected from the group consisting of Si,Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping includessurfactant (e.g., In) enhanced n-doping. In some embodiments, the methodfurther includes other group IV element doping (e.g., in someembodiments, Ge or Sn) instead of, or in addition to, the elementsrecited above.

FIG. 6A is a table 601 of thicknesses (in nanometers) for the AlN andGaN layers set forth in GaN structure 301 of FIG. 3. In someembodiments, each row of table 601 refers to a range of thicknesses forthe AlN layer (e.g., layer 306 of FIG. 3) and a corresponding range ofthicknesses for at least one of the GaN layers (e.g., layer 307 and/orlayer 308 of FIG. 3). In some embodiments, thickness of the AlN layer isin a range of approximately one monolayer to 210 nanometers (nm), andthe thickness of the GaN layer(s) is in a range of approximately 10 to20,000 nm.

FIG. 6B is a continuation of table 601.

FIG. 7A is a table 701 showing the Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction (XRD) values (in arcseconds) forGaN produced according to some embodiments of the present invention.Table 701 includes rocking curve values for both the 002 (symmetric) and102 (asymmetric) peaks. In some embodiments, the rocking curve valuesgenerally decrease with decreasing AlN thickness. In some embodiments,the smaller rocking curve values are generally more favorable.

FIG. 7B is a continuation of table 701. In some embodiments, the FWHMvalue for the GaN 002 peak is in a range of approximately 14.4 to 619arcseconds, and the FWHM value for the GaN 102 peak is in a range ofapproximately 0 to 2515 arcseconds. In some embodiments, the presentinvention provides a combination of 002 peak values below 250 arcsecondsand 102 peak values below 550 arcseconds with the AlN thicknessespresented in table 1201 and sputtering processes (see table 1301 forsome FWHM embodiments provided by the present invention; each row intable 1301 refers to a range of FWHM values for the GaN 002 and 102peaks).

In some embodiments, the present invention provides a method forproducing a gallium nitride (GaN)-based device that includes providing asubstrate; sputtering aluminum nitride (AlN) onto the substrate; andsputtering at least a first layer of GaN onto the AlN such that thefirst layer of GaN has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction (XRD) measurement for a 002 peak that is lessthan 250 arcseconds and a FWHM XRD measurement for a 102 peak that isless than 550 arcseconds.

In some embodiments of the method, the first layer of GaN has athickness in a range of approximately 10 to 20000 nanometers (nm), andwherein the AlN has a thickness in a range of approximately 5 to 210 nm.

In some embodiments, the present invention provides a gallium-nitride(GaN)-based device that includes a substrate; a first layer of aluminumnitride (AlN) on the substrate; and at least a second layer of GaN onthe first layer of AlN, wherein the second layer of GaN has an Omegarocking curve full-width half-maximum (FWHM) X-ray diffraction (XRD)measurement for a 002 peak that is less than 250 arcseconds and a FWHMXRD measurement for a 102 peak that is less than 550 arcseconds.

In some embodiments of the apparatus, the first layer of GaN has athickness in a range of approximately 10 to 20000 nanometers (nm),wherein the AlN has a thickness in a range of approximately onemonolayer to 210 nm.

In some embodiments, the present invention provides a method for growinggallium-polar (Ga-polar) gallium nitride (GaN) on sapphire (in some suchembodiments, the sapphire is substantially a c-plane-oriented sapphire;in some embodiments, a substantially r-plane-oriented sapphire; in someembodiments, a substantially m-plane-oriented sapphire; in someembodiments, a substantially a-plane-oriented sapphire). In someembodiments, the method includes any one or more of the following: (1)substrate preparation (in some embodiments, step 1 is optional), whereinthe substrate preparation includes (a) chemical cleaning (epi-ready,and/or degrease, and/or chemical etch), and (b) vacuum outgassing withlower pressures and higher temperatures than atmosphere (e.g., in someembodiments, vacuum below 1e⁻⁶ Torrs, substrate temperature of 800 to900 degrees C.); (2) surface nitridation, wherein the surfacenitridation includes (a) providing N₂ radio frequency (RF) plasma withan RF power, an N₂ flow rate, and at a substrate temperature for aduration of time (e.g., in some embodiments, RF power: 300-500 watts(W), N₂ flow: 2-9 standard cubic centimeters per minute (SCCM),substrate temperature: 300 to 900 degrees C., duration: 10 to 60minutes), and (b) optionally monitoring reflection high-energy electrondiffraction (RHEED) during nitridation; (3) forming an AlN buffer (insome embodiments, step 3 is optional), wherein the forming of the AlNbuffer includes (a) depositing a layer of AlN (e.g., in someembodiments, 5 nanometers (nm) to 50 nm of AlN (or AlGaN)) with an RFpower on the magnetron gun, a nitrogen flow, an elevated substratetemperature, and an Al/N flux ratio (for example, in some embodiments,RF power: 300-800 W, N₂ flow: 2 to 5 SCCM, substrate temperature: 700 to850 C, and Al/N flux slightly greater than 1:1), (b) in someembodiments, depositing Al for 5 seconds, then providing 10 seconds ofRF active nitrogen plasma (once or more), then depositing AlN for 1minute followed by 30 seconds of annealing (once or more), then a lastN₂ anneal (just enough to use extra Al on surface), (c) optionallymonitoring RHEED pattern change from sapphire to diffused AlN to streakyAlN, and (d) optionally using optical reflectometry to monitor extrametal anneal times. In some embodiments, if the template is AlN asdescribed in steps (1) through (3) above, then gallium is deposited andsubsequently evaporated to remove any oxygen from the AlN surface. Insome embodiments, the method further includes: (4) GaN nucleation,wherein the GaN nucleation includes (a) providing 10 to 100 nm of hightemperature, N-rich GaN (for example in some embodiments, RF power:300-500 W, N₂ flow: 2 to 5 SCCM, substrate temperature: 700 to 850 C,Ga/N flux ratio less than 1:1), (b) optionally monitoring RHEED patternfrom streaky to extended chevron (two-dimensional (2D) tothree-dimensional (3D) diffraction), (c) optionally monitoringreflectometry intensity corresponding to intentional surface roughening;(5) forming a GaN smoothing layer, wherein the forming of the GaNsmoothing layer includes (a) providing 100 to 500 nm of hightemperature, Ga-rich GaN (for example, in some embodiments, RF power:300-500 W, N₂ flow: 2 to 5 SCCM, substrate temperature: 700 to 850 C,Ga/N flux ratio greater than 1:1), (b) desorbing extra Ga under N₂ (RFplasma off) at an elevated substrate temperature (for example, in someembodiments, 700 to 800 C), (c) optionally monitoring RHEED pattern fromextended chevron to streaky (3D to 2D diffraction); (6) forming a thickGaN defect-reduction layer, wherein the forming of the GaNdefect-reduction layer includes (a) providing 1 to 5 μm of slightlyGa-rich GaN (for example, in some embodiments, RF power: 300-500 W, N₂flow: 2 to 5 SCCM, substrate temperature: 400 to 800 C, Ga/N flux ratioapproximately greater than 1:1, growth rate greater than 0.1 μm/hour),(b) every approximately 15 to 30 minutes, desorbing extra Ga under N₂(RF plasma off) at an elevated substrate temperature (for example, insome embodiments, 700 to 800 C), (c) optionally monitoring RHEED patternshowing sharper streaks with increasing GaN thickness, (d) optionallyusing optical reflectometry to monitor growth rate, changes in growthmode, and extra Ga anneal times, (e) optionally using a defect-reductiontechnique such as epitaxial atomic layer sputtering (EALS),plasma-enhanced epitaxy, glancing angle ion-assisted growth, thin AlNinter-layers and AlN/GaN short period superlattice, or any othersuitable defect reduction technique, (f) optionally using a dopingmethod such as described above (for example, in some embodiments, diluteconcentration of SiH₄ in nitrogen is injected into the chamber).

In some embodiments, the present invention provides Group IIIA-nitrideAlN/GaN and AlN/AlGaN superlattice (SL) structures used for threadingdislocation (TD) density reduction (i.e., TD filtering) and/or forstrain control and engineering in GaN and AlGaN layers and structuresgrown on sapphire and silicon substrates. In some such embodiments, thesputtering techniques described herein (including, in some embodiments,epitaxial atomic layer sputtering (EALS)) are used to form thehigh-quality TD filtering and strain-control structures at much lowergrowth temperatures than conventional methods. In some embodiments, theGroup IIIA-nitride SL structures include 50-100 periods of 3 nm-5 nm AlNand 10 nm-30 nm GaN or AlGaN grown under conditions that promote smoothinterfaces. In some embodiments, the present invention provides SLstructures that include periodic lattice-matchedIII-nitride/metal-nitride layers, such as GaN/HfN and GaN/ZrN SLs (insome such embodiments, the SL structures additionally have a highout-of-plane electrical conductivity compared to AlN/GaN SLs because ofvery high resistivity of AlN).

In some embodiments, the present invention provides a method forproducing a gallium nitride (GaN)-based device that includes providing asubstrate template that includes aluminum nitride; depositing one ormore gallium nitride (GaN) nucleation layers on the substrate template;depositing a GaN smoothing layer onto the one or more GaN nucleationlayers; and depositing a thick GaN defect-reduction layer onto the GaNsmoothing layer.

In some embodiments, sputter epitaxy provides a plurality of benefitsincluding (1) no metal organic precursors, (2) lower processtemperatures (as compared to conventional epitaxy techniques), (3)larger wafers, and (4) superior thermal budget, which enablesintegration.

In some embodiments, the present invention provides a system and methodthat includes: PVD (e.g., in some embodiments, sputtering) of an AlNNucleation Layer (in some embodiments, 5 minutes of PVD can replace upto about 1.5 hours of MOCVD), PVD of a GaN:Hf template (in someembodiments, about 500 nm of GaN:Hf can replace up to about 5 μm ofMOCVD GaN since the conductivity of GaN:Hf is so high), PVD of aHfN/GaN:Hf distributed Bragg reflector (DBR) template (in someembodiments, the PVD of the HfN/GaN:Hf DBR template enables opticalmicrocavity devices that are lattice-matched to GaN, and have 99.99%reflectivity and high conductivity).

FIG. 8A is a schematic diagram of a template and device epitaxy system801 for electronics and solid-state lighting (SSL). In some embodiments,system 801 performs processing on a bare wafer 850 in order to produce ametal-mirror device 860. In some embodiments, system 801 includes aplurality of modules 805-810 (in some such embodiments, each one of theplurality of modules 805-810 is a separate deposition chamber; in otherembodiments, the plurality of modules 805-810 is contained within asingle deposition chamber). In some embodiments, system 801 includes analuminum nitride (AlN)-nucleation module 805 configured to generate anucleation layer of AlN (in some such embodiments, the AlN nucleationlayer has a thickness of approximately 25 nanometers (nm)) using one ormore of the PVD processes described herein. In some embodiments, system801 further includes a grown-epitaxial metal mirror (GEMM) module 806configured to generate one or more GEMM layers (in some suchembodiments, the GEMM layer(s) is generated according to thedescriptions in U.S. Pat. Nos. 7,915,624, 8,253,157, and/or 8,890,183,which were introduced above and incorporated herein by reference). Insome embodiments, system 801 further includes GaN modules 807, 808, 809,and 810, which are configured to generate one or more GaN layers usingone or more of the PVD processes described herein (e.g., in someembodiments, one or more layers of Hf:GaN are generated at GaN modules807, 808, 809, and/or 810).

FIG. 8B is a schematic diagram of a template and device epitaxy system802 for electronics and SSL. In some embodiments, system 802 performsprocessing on a bare wafer 850 in order to produce an LED-ready device870. In some embodiments, system 802 includes a plurality of modules805-808 and 820-821 (in some such embodiments, each one of the pluralityof modules 805-808 and 820-821 is a separate deposition chamber; inother embodiments, the plurality of modules 805-808 and 820-821 iscontained within a single deposition chamber). In some embodiments,instead of GaN modules 809 and 810, system 802 includes MOCVD modules821 and 822, which are configured to provide MOCVD processing.

FIG. 9 is a schematic diagram of a template and device epitaxy process901 for electronics and SSL. In some embodiments, process 901 includessteps (A), (B), and (C). In some embodiments, step (A) includesgenerating a nucleation layer of AlN 906 on a sapphire substrate 905using one or more of the PVD processes described herein (e.g., in someembodiments, sputtering), wherein the AlN nucleation layer 906 has athickness of approximately 25 nm (in some such embodiments, step (A) isperformed at module 805 of FIG. 8A). In some embodiments, step (B)includes generating a layer 907 of Hf:GaN on the AlN nucleation layer906 using one or more of the PVD processes described herein (e.g., insome embodiments, sputtering). In some embodiments, step (B) isperformed at modules 807, 808, 809, and/or 810 of FIG. 8A. In someembodiments, step (C) includes generating N periods of alternatinglayers of Hf:GaN and HfN (e.g., distributed Bragg reflectors) 908 onlayer 907 based on the GEMM descriptions in U.S. Pat. Nos. 7,915,624,8,253,157, and/or 8,890,183, which were introduced above andincorporated herein by reference (in some such embodiments, step (C) isperformed at GEMM module 806 of FIG. 8A). In some embodiments, any oneor more of steps (A), (B), and (C) further includes generating a layer920 of n-type GaN and a layer 921 of p-type GaN/multiple quantum wells(MQWs) using a MOCVD process (in some such embodiments, layer 920 has athickness of approximately 5 micrometers (μm); in other suchembodiments, layer 920 has a thickness of approximately less than 1 μm).In some embodiments, layers 920 and 921 are generated at modules 920and/or 921 of FIG. 8B.

FIG. 10 is a graph 1001 showing n-type carrier concentration (per cubiccentimeter) versus adatom mobility (cm²/V·s) for hafnium-doped galliumnitride produced according to some embodiments of the present invention.

FIG. 11 is a graph 1101 showing the X-ray diffraction (XRD) data for GaNproduced according to some embodiments of the present invention. In someembodiments, the Omega rocking curve full-width half-maximum (FWHM)value for the 002 peak is 300 arcseconds.

FIG. 12 is a schematic diagram of a GaN template structure 1201 forsubsequent LED epitaxial growth. In some embodiments, structure 1201includes one or more indium tin oxide (ITO) replacement layers for usewith thin film and standard light emitting devices. In some embodiments,the ITO replacement layer(s) is textured (e.g., pyramids, domes, 2Dphotonic crystals, and the like) and includes a GaN doped with atransitional metal element to form a textured transitional metal dopedGaN such as Hf:GaN, Hf:AlGaN, Hf:InGaN, Hf:InGaAlN, or the like. In someembodiments, for p-side-up devices, the ITO replacement layer includes alayer 1205 of Hf:GaN placed directly on top of the p-type GaN/MQWslayer(s) 921, and a layer 1206 of Si:GaN (in some such embodiments,having a thickness of less than 1 μm) placed directly below the p-typeGaN/MQWs layer(s) 921. In some embodiments, for p-side-down devices, theITO replacement layer includes a layer 1207 of Hf:GaN placed directly ontop of the AlN nucleation layer(s) 906. In some embodiments, the PVDprocesses for generating Hf:GaN described herein (e.g., sputtering) havelow process temperatures, which allow the ITO layer(s) to be used bothpre and post epitaxy (accordingly, in some such embodiments, there is noneed for tetrakis dimethylamino hafnium, which is commonly used in MOCVDsystems).

FIG. 13 is a schematic diagram of an epitaxial stack structure 1301 ofGEMM/GaN. In some embodiments, structure 1301 includes a substrate layer1305 of sapphire (Al₂O₃) and five periods 1306 of alternating layers ofGEMM and GaN. In some embodiments, structure 1301 is lattice matched forepi-ready growth, highly conductive (low resistivity value), and higherin reflectivity than AlN/GaN distributed Bragg reflectors (DBRs). Insome embodiments, the GEMM growth is performed according to thedescriptions in U.S. Pat. Nos. 7,915,624, 8,253,157, and/or 8,890,183,which were introduced above and incorporated herein by reference.

FIG. 14A is a graph 1401 of X-ray diffraction (XRD) data for GaNproduced according to some embodiments of the present invention. In someembodiments, the GaN is lattice matched with a low rocking curvefull-width half-maximum (FWHM) value (e.g., in some embodiments, a 0.35%mismatch).

FIG. 14B is a graph 1402 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 14C is a graph 1403 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 14D is a graph 1404 of X-ray diffraction (XRD) data for the GaNproduced according to some embodiments of the present invention.

FIG. 15 is a diagram 1501 of atomic-force microscopy (AFM) data for GaNon GEMM produced according to some embodiments of the present invention.In some embodiments, the GaN on GEMM has an ultra-smooth atomic stepsurface that allows uniform growth of thin quantum wells.

FIG. 16 is a graph 1601 showing a comparison between reflectivity ofGEMM/GaN produced according to some embodiments of the present invention(solid line) versus conventional AlN/GaN distributed Bragg reflectors(DBRs) (dashed line). In some embodiments, the center wavelength λ₀ islocated between 400 nanometers (nm) and 700 nm, depending on materialsselection and thicknesses.

FIG. 17 is a graph 1701 of estimated sputtering yield for galliumnitride (GaN) versus temperature of the gallium target. Graph 1701 showsthat, in some embodiments, when the gallium target temperature is inregion 1705 (i.e., greater than approximately 14 degrees Celsius (C)),the estimated sputtering yield is temperature sensitive. In contrast,graph 1701 shows that, in some embodiments, when the gallium targettemperature is in region 1706 (i.e., less than approximately 14 degreesC.), the estimated sputtering yield is temperature insensitive. Graph1701 further shows that, in some embodiments, the melting point ofgallium 1799 (approximately 29 degrees C.) falls withintemperature-sensitive region 1705. In some embodiments, the presentinvention cools the gallium target such that it is withintemperature-insensitive region 1706. In some embodiments, the cooling ofthe gallium target includes providing a temperature gradient across thedepth of the gallium target such that a first depth of the galliumtarget is at a first temperature and a second depth it at a secondtemperature.

In some embodiments, the temperature of the gallium target is kept lowfor reliable repeatable manufacturing as well as high-quality films. Insome embodiments, if the gallium is a liquid, gallium spitting on thewafer may inhibit manufacturing. In some embodiments, if the target iskept at a temperature near gallium's melting point 1799 (e.g., +/− 20degrees C. or more relative to melting point 1799), the yield of ejectedatoms will be highly dependent on slight changes in the processparameters and the energies of the ejected atoms will have a broaddistribution.

In some embodiments, reducing the temperature of the gallium sputteringtarget below 28 degrees Celsius (C) and lower improves the repeatabilityand quality of the resulting gallium nitride (GaN) films. In someembodiments, the quality of the resulting GaN films improves down to −40degrees C., and, in some embodiments, reducing the temperature evenfurther (e.g., −200 degrees C.) provides additional improvements in GaNcrystal quality. In some embodiments, the reason for the improved filmquality is due to a refinement of the gallium purity during thesputtering process where impurities have a lower sputtering yield atlower target temperatures. Additionally, in some embodiments, theimprovement is due to a reduction in “gallium spitting” where plasmagases (e.g., noble gases and possibly reactive gases) have a moreshallow penetration into the gallium target. In some embodiments, thepresent invention includes noble gases for sputtering and ion sources(e.g., in some embodiments, helium (He), neon (Ne), argon (Ar), krypton(Kr), xenon (Xe), radon (Rn), and/or oganesson (Og)).

In some embodiments of the epitaxial atomic layer sputtering (EALS)provided by the present invention, the gallium sputtering target is keptsolid and colder than its melting point by at least 15 degrees Celsius(C). In some embodiments, the temperature of the gallium sputteringtarget is equal to or between 0 degrees C. and 15 degrees C., inclusive;in some embodiments, the target temperature is between −15 degrees C.and 0 degrees C., inclusive; in some embodiments, the target temperatureis equal to or between −40 degrees C. and −15 degrees C., inclusive; insome embodiments, the target temperature is equal to or between −100degrees C. and −40 degrees C., inclusive; in some embodiments, thetarget temperature is equal to or between −200 degrees C. and −100degrees C., inclusive; in some embodiments, the target temperature islower than −200 degrees C. In some embodiments, the gallium sputteringtarget temperature is between 14 degrees C. and −273 degrees C.

In some embodiments, the present invention provides a method forproducing a gallium nitride (GaN)-based device that includes providing asubstrate template that includes aluminum nitride; and depositing atextured transitional metal doped GaN layer onto the substrate template.

Conventional techniques avoid gallium deposition by sputtering due togallium's low melting point (approximately 29 degrees C.), especiallywhen the wafer temperature is higher than in most applications byhundreds of degrees and the wafer-to-target distance is just centimetersaway.

In some embodiments, the present invention provides GaN growth bysputtering from a gallium target (solid or liquid) with an XRD 102 peakwith a FWHM below about 3000 arcseconds. In some embodiments, thepresent invention provides GaN for use with high-electron-mobilitytransistors, wherein the GaN has an XRD 102 peak with a FWHM below 1500arcsec. In some embodiments, the present invention provides GaN for usewith light emitting devices, wherein the GaN has an XRD 102 peak with aFWHM below 600 arcseconds (e.g., 300 arcseconds). In some embodiments,the present invention provides smooth non-columnar step growth of GaN byPVD (e.g., sputtering). In some such embodiments, the gallium target ismaintained below 14 degrees C. (in some embodiments, the gallium targetis maintained at subzero Celsius temperatures and non-waterheat-transfer liquids such as alcohols are used). In some embodiments,the present invention provides EALS processes to achievecommercial-grade atomic-force microscopy (AFM), optical, and X-raydiffraction (XRD) results.

In some embodiments, the present invention provides an epitaxial atomiclayer sputtering (EALS) process (e.g., GaN growth on GaN, AlN,nucleation layer (described below) or similar template) that includesany one or more of the following: (1) high-temperature annealing; (2) ata higher temperature than normal (e.g., by 20 degrees C. to 50 degreesC. greater), growing Ga:N at a ratio of greater than 1 for 5 to 20minutes; (3) in a normal growth mode (e.g., 700 degrees C.), growingGa:N at a ratio of greater than 1 for 20 to 40 minutes; (4a) stop growthand anneal at 750 degrees C. until all excess gallium is evaporated andfilm is smooth (e.g., anneal for 5 to 10 minutes) or (4b) continuegrowth but with Ga:N ratio of less than 1 (in some such embodiments,gallium may be turned off or the shutter may be closed); and (5) repeatsteps 1 through 4. In some embodiments, at any time during the abovesteps, RF nitrogen is used instead of N₂ or NH₃ gases while argon issupplied directly to the gallium target, and in some embodiments, an ionsource from the gallium target or a separate ion source is used. In someembodiments, doping with hafnium (Hf), zirconium (Zr), silicon (Si),germanium (Ge), magnesium (Mg), copper (Cu), or any of the othertransitional metals is done during the above steps. In some embodiments,alloying GaN with aluminum (Al), indium (In), or any of the othertransitional metals including Hf, Zr, or scandium (Sc) is done duringthe above steps.

In some embodiments, the present invention provides a process forgenerating a nucleation layer on a dissimilar template (e.g., Si,sapphire, hafnium nitride (HfN), zirconium nitride (ZrN), zinc oxide(ZnO), glass, or the like), wherein the process includes any one or moreof the following: (1) thermal cleaning, thermal texturing, chemicallyassisted; (2) nitridation at elevated temperatures by exposing tonitrogen source including N₂, nitrogen ions, NH₃ or the like; and (3)deposition of AlN (optional GaN) to a thickness in a range of about 5nanometers (nm) to 100 nm by sputtering. In some embodiments, at anytime during the above steps, RF nitrogen is used instead of N₂ or NH₃gases while argon is supplied directly to the gallium target, and insome embodiments, an ion source from the gallium target or a separateion source is used. In some embodiments, doping with Hf, Zr, Si, Ge, Mg,Cu, or any of the other transitional metals is done during the abovesteps. In some embodiments, alloying GaN with Al, In, or any of theother transitional metals including, for example, Hf, Zr, or Sc is doneduring the above steps.

FIG. 18 is a schematic diagram of a sputtering system 1801. In someembodiments, system 1801 includes a plurality of gallium (Ga) gunsincluding Ga gun 1810 (positioned at zero degrees from template 1805),Ga gun 1811 (positioned at 45 degrees from template 1805), and Ga gun1812 (positioned 90 degrees from template 1805). In some embodiments,system 1801 further includes a plurality of ion sources 1820 and/or1821. In some embodiments, template 1805 is rotated between the Ga guns1810-1812 and ion sources 1820 and/or 1821. In some embodiments, formanufacturing stability as well as for the quality of the groupIIIA-nitride films, it is important to provide enough ions to thesurface by either sputtering gun or ion gun. In some embodiments, theion gun is replaced with a photon source (e.g. ultraviolet) or anelectron source. In some embodiments, the ion source (e.g., ion source1820 and/or ion source 1821), whether it be from a dedicated-ion sourceor from a sputtering target, is best when provided at between shallowangle and 90 degrees to the surface of template 1805. In someembodiments, while these components are in place, argon is fed to thesputtering gun and the amount of nitrogen interaction with the galliumtarget is minimized to run processes in a reduced nitrogen poisoningregime.

In some embodiments, the present invention provides a method forepitaxially growing a gallium nitride (GaN) structure that includesproviding a substrate; growing at least a first GaN layer on a surfaceof the substrate using a first physical vapor deposition (PVD) process(e.g., in some embodiments, sputtering), wherein the first PVD processincludes: providing a solid gallium target, and maintaining the solidgallium target at a first temperature that is less than approximately 29degrees Celsius.

In some embodiments of the method, the providing of the substrateincludes growing an aluminum nitride (AlN) layer on a base of thesubstrate using a second PVD process (e.g., in some embodiments,sputtering) such that the AlN layer forms the surface of the substrate.In some embodiments, the first PVD process further includes epitaxialatomic layer sputtering (EALS). In some embodiments, the first PVDprocess further includes EALS, wherein the EALS includes heating thesubstrate. In some embodiments, the first PVD process further includesmagnetron sputtering. In some embodiments, the first temperature is lessthan approximately 15 degrees Celsius. In some embodiments, themaintaining of the solid gallium target at the first temperatureincludes fluid-convection cooling the solid gallium target using analcohol-based fluid. In some embodiments, the first GaN layer has anOmega rocking curve full-width half-maximum (FWHM) X-ray diffractionmeasurement for both 002 and 102 peaks that is less than approximately1000 arcseconds.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a substrate;and growing at least a first GaN layer on a surface of the substrateusing a first physical vapor deposition (PVD) process (e.g., in someembodiments, a first sputtering process), wherein the first PVD processincludes: providing a solid gallium target, wherein the providing of thesolid gallium target includes maintaining the solid gallium target at afirst temperature, and implementing epitaxial atomic layer sputtering(EALS) of the at least first GaN layer such that the growing of the atleast first GaN layer includes non-columnar step growth of the at leastfirst GaN layer.

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes a load lock configuredto load a substrate wafer into the system and remove the GaN structurefrom the system; and a plurality of deposition modules, wherein theplurality of deposition modules includes a GaN-deposition moduleconfigured to grow at least a first GaN layer on a surface of thesubstrate wafer via a first physical vapor deposition (PVD) process(e.g., in some embodiments, a first sputtering process), wherein theGaN-deposition module includes a solid gallium target that is maintainedat a first temperature, and wherein the first PVD process includesepitaxial atomic layer sputtering (EALS) of the at least first GaN layersuch that non-columnar step growth of the at least first GaN layeroccurs.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a substrate;and growing at least a first GaN layer on a surface of the substrateusing a first sputtering process, wherein the first sputtering processincludes: providing a gallium target, and implementing epitaxial atomiclayer sputtering (EALS) such that the growing of the at least first GaNlayer includes non-columnar step growth of the at least first GaN layer.

In some embodiments, the implementing of the MEE includes controlling aratio of gallium-to-nitrogen to be greater than 1-to-1 for at least afirst time period of the first sputtering process. In some embodimentsof the method, the implementing of the MEE includes introducing nitrogenvia a radio frequency (RF) nitrogen source.

In some embodiments of the method, the first sputtering process furtherincludes doping the at least first GaN layer with silicon (Si). In someembodiments, the first sputtering process further includes doping the atleast first GaN layer by gas injecting a reactant with a carrier gasholding silicon (Si).

In some embodiments of the method, the gallium target is a solid galliumtarget, wherein the first sputtering process further includesmaintaining the solid gallium target at a first temperature that is lessthan approximately 15 degrees Celsius. In some embodiments, the galliumtarget is a solid gallium target, wherein the first sputtering processfurther includes maintaining the solid gallium target at a firsttemperature, and wherein the maintaining of the solid gallium target atthe first temperature includes fluid-convection cooling the solidgallium target using an alcohol-based fluid.

In some embodiments of the method, the providing of the substrateincludes growing an aluminum nitride (AlN) layer on a base of thesubstrate using a second sputtering process such that the AlN layerforms the surface of the substrate. In some embodiments, the methodfurther includes growing a grown-epitaxial metal mirror (GEMM) on the atleast first GaN layer. In some embodiments, the method further includesgrowing a grown-epitaxial metal mirror (GEMM) on the at least first GaNlayer, wherein the GEMM includes alternating layers of hafnium (Hf):GaNand hafnium nitride (HfN). In some embodiments, the method furtherincludes growing a grown-epitaxial metal mirror (GEMM) on the at leastfirst GaN layer, wherein the GEMM includes alternating layers of hafnium(Hf):GaN and hafnium nitride (HfN); and growing at least a first quantumwell on a surface of the GEMM using a metal-organic chemical vapordeposition (MOCVD) process. In some embodiments, the first sputteringprocess further includes magnetron sputtering. In some embodiments, theat least first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for both 002 and 102peaks that is less than approximately 1000 arcseconds. In someembodiments, the at least first GaN layer has an Omega rocking curvefull-width half-maximum (FWHM) X-ray diffraction measurement for a 002peak that is in a range of about 10 arcseconds to about 2500 arcseconds.

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes a load lock configuredto load a substrate wafer into the system and remove the GaN structurefrom the system; and a plurality of deposition chambers, wherein theplurality of deposition chambers includes a GaN-deposition chamberconfigured to grow at least a first GaN layer on a surface of thesubstrate wafer via a first sputtering process, and wherein the firstsputtering process includes epitaxial atomic layer sputtering (EALS) ofthe at least first GaN layer such that non-columnar step growth of theat least first GaN layer occurs.

In some embodiments, the system further includes a wafer-handlingmechanism configured to automatically transfer the substrate waferbetween the plurality of deposition chambers. In some embodiments, theplurality of deposition chambers includes an aluminum nitride(AlN)-deposition chamber configured to grow an AlN layer on a base ofthe substrate wafer via a second sputtering process such that the AlNlayer forms the surface of the substrate wafer. In some embodiments, theplurality of deposition chambers includes a grown-epitaxial metal mirror(GEMM)-deposition chamber configured to grow a GEMM on the at leastfirst GaN layer. In some embodiments, the GaN-deposition chamberincludes a solid gallium target that is maintained at a firsttemperature, and wherein the first temperature is less thanapproximately 15 degrees Celsius. In some embodiments, theGaN-deposition chamber further includes: a solid gallium target that ismaintained at a first temperature; and a fluid-convection coolerconfigured to cool the solid gallium target via an alcohol-based fluid.

In some embodiments, the GaN-deposition chamber is further configured todope the at least first GaN layer with silicon (Si). In someembodiments, the GaN-deposition chamber is further configured to growthe at least first GaN layer such that the at least first GaN layer hasan Omega rocking curve full-width half-maximum (FWHM) X-ray diffractionmeasurement for both 002 and 102 peaks that is less than approximately1000 arcseconds. In some embodiments, the GaN-deposition chamber isfurther configured to grow the at least first GaN layer such that the atleast first GaN layer has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction measurement for a 002 peak that is in a rangeof about 10 arcseconds to about 2500 arcseconds.

In some embodiments, the plurality of deposition chambers furtherincludes: an aluminum nitride (AlN)-deposition chamber configured togrow an AlN layer on a base of the substrate wafer via a secondsputtering process such that the AlN layer forms the surface of thesubstrate wafer; a grown-epitaxial metal mirror (GEMM)-depositionchamber configured to grow a GEMM on the at least first GaN layer,wherein the GEMM includes alternating layers of hafnium (Hf):GaN andhafnium nitride (HfN); and a metal-organic chemical vapor deposition(MOCVD) chamber configured to grow at least a first quantum well on asurface of the GEMM.

In some embodiments, the present invention provides a gallium-nitridestructure that includes a substrate; and at least a first galliumnitride (GaN) layer grown on a surface of the substrate, wherein the atleast first GaN layer has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction measurement for both 002 and 102 peaks that isless than approximately 1000 arcseconds (in some embodiments, the atleast first GaN layer has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction measurement for a 002 peak that is in a rangeof about 10 arcseconds to about 2500 arcseconds).

In some embodiments, the structure further includes an aluminum nitride(AlN) layer grown on a base of the substrate such that the AlN layerforms the surface of the substrate. In some embodiments, the structurefurther includes a grown-epitaxial metal mirror (GEMM) grown on asurface of the at least first GaN layer. In some embodiments, thesubstrate includes sapphire, the structure further including an aluminumnitride (AlN) layer on a base of the substrate such that the AlN layerforms the surface of the substrate; a grown-epitaxial metal mirror(GEMM) grown on a surface of the at least first GaN layer, wherein theGEMM includes alternating layers of hafnium (Hf):GaN and hafnium nitride(HfN); a layer of n-type GaN grown on a surface of the GEMM; and a layerof p-type GaN/multiple quantum wells (MQWs) grown on the layer of n-typeGaN.

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes means for loading asubstrate wafer into the system; and means for sputtering at least afirst GaN layer on a surface of the substrate wafer, wherein the meansfor sputtering the at least first GaN layer includes means forimplementing epitaxial atomic layer sputtering (EALS) such thatnon-columnar step growth of the at least first GaN layer occurs.

In some embodiments of the system, the means for sputtering includesmeans for doping the at least first GaN layer with silicon (Si). In someembodiments, the system further includes means for growing an aluminumnitride (AlN) layer on a base of the substrate such that the AlN layerforms the surface of the substrate. In some embodiments, the systemfurther includes means for growing a grown-epitaxial metal mirror (GEMM)on the at least first GaN layer, wherein the GEMM includes alternatinglayers of hafnium (Hf):GaN and hafnium nitride (HfN). In someembodiments, the system further includes: means for growing agrown-epitaxial metal mirror (GEMM) on the at least first GaN layer,wherein the GEMM includes alternating layers of hafnium (Hf):GaN andhafnium nitride (HfN); and means for growing at least a first quantumwell on a surface of the GEMM.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a template;and growing at least a first GaN layer on the template using a firstsputtering process, wherein the first sputtering process includes:controlling a temperature of a sputtering target, and modulating backand forth between a gallium-rich condition and a gallium-lean condition,wherein the gallium-rich condition includes a gallium-to-nitrogen ratiohaving a first value that is greater than 1, and wherein thegallium-lean condition includes the gallium-to-nitrogen ratio having asecond value that is less than 1.

In some embodiments of the method, the first sputtering process furtherincludes introducing nitrogen via a radio frequency (RF) nitrogensource. In some embodiments, the first sputtering process furtherincludes doping the at least first GaN layer with silicon (Si). In someembodiments, the first sputtering process further includes doping the atleast first GaN layer by gas injecting a reactant with a carrier gasholding silicon (Si). In some embodiments, the sputtering target is asolid gallium target, wherein the controlling of the temperature of thesolid gallium target includes maintaining the temperature at a firsttemperature value that is less than approximately 14 degrees Celsius. Insome embodiments, the sputtering target is a solid gallium target, andwherein the controlling of the temperature of the solid gallium targetincludes fluid-convection cooling the solid gallium target using analcohol as a heat-transfer fluid.

In some embodiments of the method, the providing of the templateincludes growing an aluminum nitride (AlN) layer on the template. Insome embodiments, the providing of the template includes growing analuminum nitride (AlN) layer on the template using a second sputteringprocess. In some embodiments, the providing of the template includesgrowing a first aluminum nitride (AlN) layer on the template using asecond sputtering process, wherein the method further includes growing asecond aluminum nitride (AlN) layer on the at least first GaN layerusing the second sputtering process; and growing a second GaN layer onthe second AlN layer using the first sputtering process.

In some embodiments, the method further includes growing agrown-epitaxial metal mirror (GEMM) on the at least first GaN layer,wherein the GEMM includes alternating layers of hafnium (Hf):GaN andhafnium nitride (HfN). In some embodiments, the method further includesgrowing a grown-epitaxial metal mirror (GEMM) on the at least first GaNlayer, wherein the GEMM includes alternating layers of hafnium (Hf):GaNand hafnium nitride (HfN); and growing at least a first quantum well ona surface of the GEMM using a metal-organic chemical vapor deposition(MOCVD) process. In some embodiments, the first sputtering processfurther includes magnetron sputtering. In some embodiments, the at leastfirst GaN layer has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction measurement for a 002 peak that is in a rangeof about 10 arcseconds to about 2500 arcseconds.

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes a load lock configuredto load a substrate wafer into the system and remove the GaN structurefrom the system; and a plurality of deposition chambers, wherein theplurality of deposition chambers includes a GaN-deposition chamberconfigured to grow at least a first GaN layer on a template thatincludes the substrate wafer via a first sputtering process, and whereinthe first sputtering process includes a modulation back and forthbetween a gallium-rich condition and a gallium-lean condition, whereinthe gallium-rich condition includes a gallium-to-nitrogen ratio having afirst value that is greater than 1, and wherein the gallium-leancondition includes the gallium-to-nitrogen ratio having a second valuethat is less than 1.

In some embodiments, the system further includes a wafer-handlingmechanism configured to automatically transfer the template between theplurality of deposition chambers. In some embodiments, the plurality ofdeposition chambers includes an aluminum nitride (AlN)-depositionchamber configured to grow an AlN layer on the substrate wafer to formthe template via a second sputtering process. In some embodiments, theplurality of deposition chambers includes a grown-epitaxial metal mirror(GEMM)-deposition chamber configured to grow a GEMM on the at leastfirst GaN layer. In some embodiments, the GaN-deposition chamberincludes a solid gallium target that is maintained at a firsttemperature, and wherein the first temperature is less thanapproximately 14 degrees Celsius. In some embodiments, theGaN-deposition chamber further includes: a solid gallium target that ismaintained at a first temperature; and a fluid-convection coolerconfigured to cool the solid gallium target via an alcohol heat-transferfluid. In some embodiments, the GaN-deposition chamber is furtherconfigured to dope the at least first GaN layer with silicon (Si). Insome embodiments, the GaN-deposition chamber is further configured togrow the at least first GaN layer such that the at least first GaN layerhas an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement for a 002 peak that is in a range of about 10arcseconds to about 2500 arcseconds. In some embodiments, the pluralityof deposition chambers further includes: an aluminum nitride(AlN)-deposition chamber configured to grow an AlN layer on thesubstrate wafer to form the template via a second sputtering process; agrown-epitaxial metal mirror (GEMM)-deposition chamber configured togrow a GEMM on the at least first GaN layer, wherein the GEMM includesalternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and ametal-organic chemical vapor deposition (MOCVD) chamber configured togrow at least a first quantum well on a surface of the GEMM.

In some embodiments, the present invention provides a gallium-nitridestructure that includes a template; and at least a first gallium nitride(GaN) layer grown on the template, wherein the at least first GaN layerhas an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement for a 002 peak that is in a range of about 10arcseconds to about 2500 arcseconds.

In some embodiments, the template includes an aluminum nitride (AlN)layer grown on a substrate. In some embodiments, the structure furtherincludes a grown-epitaxial metal mirror (GEMM) grown on a surface of theat least first GaN layer. In some embodiments, the template includes analuminum nitride (AlN) layer grown on a sapphire substrate, thestructure further including a grown-epitaxial metal mirror (GEMM) grownon a surface of the at least first GaN layer, wherein the GEMM includesalternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); alayer of n-type GaN grown on a surface of the GEMM; and a layer ofp-type GaN/multiple quantum wells (MQWs) grown on the layer of n-typeGaN.

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes means for loading asubstrate wafer into the system; and means for sputtering at least afirst GaN layer on a template that includes the substrate wafer, whereinthe means for sputtering the at least first GaN layer includes means formodulating back and forth between a gallium-rich condition and agallium-lean condition, wherein the gallium-rich condition includes agallium-to-nitrogen ratio having a first value that is greater than 1,and wherein the gallium-lean condition includes the gallium-to-nitrogenratio having a second value that is less than 1.

In some embodiments of the system, the means for sputtering includesmeans for doping the at least first GaN layer with silicon (Si). In someembodiments, the system further includes means for growing an aluminumnitride (AlN) layer on the substrate wafer to form the template. In someembodiments, the system further includes means for growing agrown-epitaxial metal mirror (GEMM) on the at least first GaN layer,wherein the GEMM includes alternating layers of hafnium (Hf):GaN andhafnium nitride (HfN). In some embodiments, the system further includesmeans for growing a grown-epitaxial metal mirror (GEMM) on the at leastfirst GaN layer, wherein the GEMM includes alternating layers of hafnium(Hf):GaN and hafnium nitride (HfN); and means for growing at least afirst quantum well on a surface of the GEMM.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a template;and growing at least a first GaN layer on the template using a firstsputtering process, wherein the first sputtering process includes:providing a gallium sputtering target, wherein the gallium sputteringtarget has a depth, and maintaining a temperature of the galliumsputtering target at a first temperature value that is less thanapproximately 14 degrees Celsius. In some embodiments, the maintainingof the temperature of the gallium sputtering target includes providing atemperature gradient across the depth of the gallium sputtering target.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a templatehaving a surface; and growing at least a first GaN layer on the templateusing a first sputtering process, wherein the first sputtering processincludes: modulating back and forth for at least a first oscillationbetween a gallium-rich condition on the surface of the template and agallium-lean condition on the surface of the template, wherein thegallium-rich condition includes a gallium-to-nitrogen ratio having afirst value that is greater than 1, and wherein the gallium-leancondition includes the gallium-to-nitrogen ratio having a second valuethat is less than the first value. In some embodiments, the modulatingback and forth includes modulating back and forth for a plurality ofoscillations including the first oscillation. In some embodiments, theat least first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for a 102 peak that isin a range of about 10 arcseconds to about 2500 arcseconds.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a template;and growing at least a first GaN layer on the template using a firstsputtering process, wherein the first sputtering process includes:providing a gallium sputtering target, wherein the gallium sputteringtarget has a depth, and maintaining a temperature of the galliumsputtering target at a first temperature value that is less thanapproximately 14 degrees Celsius. In some embodiments, the at leastfirst GaN layer has an Omega rocking curve full-width half-maximum(FWHM) X-ray diffraction measurement for a 102 peak that is in a rangeof about 10 arcseconds to about 2500 arcseconds. In some embodiments,the maintaining of the temperature of the gallium sputtering targetincludes providing a temperature gradient across the depth of thegallium sputtering target.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a template;growing a first aluminum nitride (AlN) layer on the template using afirst sputtering process; and growing a first GaN layer on the first AlNlayer using a second sputtering process. In some embodiments, the methodfurther includes growing a second AlN layer on the first GaN layer usingthe first sputtering process; and growing a second GaN layer on thesecond AlN layer using the second sputtering process. In someembodiments, the first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for a 102 peak that isin a range of about 10 arcseconds to about 2500 arcseconds.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a templatehaving a surface; and growing at least a first GaN layer on the templateusing a first sputtering process, wherein the first sputtering processincludes: growing the at least first GaN layer under at least twoconditions, wherein the two conditions include a gallium-rich conditionand a gallium-lean condition, wherein the gallium-rich conditionincludes a gallium-to-nitrogen ratio having a first value that isgreater than 1, wherein the gallium-lean condition includes thegallium-to-nitrogen ratio having a second value that is less than thefirst value; alternating between the two conditions for at least a firstgrowing under a first of the two conditions, a second growing under asecond of the two conditions after the first growing, and a thirdgrowing under the first of the two conditions after the second growing.In some embodiments, the alternating between the two conditions furtherincludes a fourth growing under the second of the two conditions afterthe third growing, and a fifth growing under the first of the twoconditions after the fourth growing. In some embodiments, the firstvalue of the gallium-to-nitrogen ratio is at least ten percent largerthan the second value of the gallium-to-nitrogen ratio. In someembodiments, the first value of the gallium-to-nitrogen ratio is atleast fifty percent larger than the second value of thegallium-to-nitrogen ratio. In some embodiments, the first value of thegallium-to-nitrogen ratio is at least two times larger than the secondvalue of the gallium-to-nitrogen ratio.

In some embodiments, the present invention provides a method for growinga gallium nitride (GaN) structure that includes providing a template;growing a first aluminum nitride (AlN) layer on the template using afirst sputtering process; and growing a first GaN layer on the first AlNlayer using a second sputtering process. In some embodiments, the methodfurther includes growing a second AlN layer on the first GaN layer usingthe first sputtering process; and growing a second GaN layer on thesecond AlN layer using the second sputtering process. In someembodiments, the first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for a 102 peak that isin a range of about 10 arcseconds to about 2500 arcseconds. In someembodiments, the method further includes growing a second AlN layer onthe first GaN layer using the first sputtering process; growing a secondGaN layer on the second AlN layer using the second sputtering process;and growing one or more layers of Al_(x)Ga_((1-x))N on the second GaNlayer, where x is between 0 and 1, inclusive. In some embodiments, themethod further includes growing a second AlN layer on the first GaNlayer using the first sputtering process; growing a second GaN layer onthe second AlN layer using the second sputtering process; and growingone or more layers of Al_(x)Ga_((1-x))N on the second GaN layer, where xvaries with depth and is between 0 and 1, inclusive. In someembodiments, the method further includes growing a second AlN layer onthe first GaN layer using the first sputtering process; growing a secondGaN layer on the second AlN layer using the second sputtering process;and growing one or more layers of compounds on the second GaN layer,wherein the compounds include one or more selected from the groupconsisting of hafnium nitride (HfN), zirconium nitride (ZrN), aluminumnitride (AlN), gallium nitride (GaN), and scandium nitride (ScN). Insome embodiments, the method further includes growing one or more layersof Al_(x)Ga_((1-x))N on the first GaN layer, where x is between 0 and 1,inclusive. In some embodiments, first sputtering process furtherincludes doping the at least first GaN layer with silicon (Si). In someembodiments, the method further includes growing one or more layers ofAl_(x)Ga_((1-x))N on the first GaN layer, where x is between 0 and 1,inclusive. In some embodiments, the method further includes growing oneor more layers of Al_(x)Ga_((1-x))N on the first GaN layer, where xvaries with depth and is between 0 and 1, inclusive. In someembodiments, the method further includes growing one or more layers ofcompounds on the first GaN layer, wherein the compounds include one ormore selected from the group consisting of hafnium nitride (HfN),zirconium nitride (ZrN), aluminum nitride (AlN), gallium nitride (GaN),and scandium nitride (ScN).

In some embodiments, the present invention provides a system for growinga gallium nitride (GaN) structure that includes a load lock configuredto load a substrate wafer into the system and remove the GaN structurefrom the system; and a plurality of deposition chambers, wherein theplurality of deposition chambers includes a first GaN-deposition chamberconfigured to grow at least a first GaN layer, via a first sputteringprocess, on a template that includes the substrate wafer, wherein thefirst GaN-deposition chamber includes a gallium sputtering target,wherein the gallium sputtering target has a depth, and wherein theGaN-deposition chamber is further configured to maintain a temperatureof the gallium sputtering target at a first temperature value that isless than approximately 14 degrees Celsius.

In some embodiments, the system further includes a wafer-handlingmechanism configured to automatically transfer the template between theplurality of deposition chambers. In some embodiments, the plurality ofdeposition chambers includes an aluminum nitride (AlN)-depositionchamber configured to grow an AlN layer, via a second sputteringprocess, on the substrate wafer to form the template. In someembodiments, the plurality of deposition chambers includes agrown-epitaxial metal mirror (GEMM)-deposition chamber configured togrow a GEMM on the at least first GaN layer. In some embodiments, thesystem further includes a fluid-convection cooler configured to cool thegallium sputtering target via an alcohol heat-transfer fluid. In someembodiments, the GaN-deposition chamber is further configured tomaintain a temperature gradient across the depth of the galliumsputtering target. In some embodiments, the plurality of depositionchambers includes a metal-organic chemical vapor deposition (MOCVD)chamber. In some embodiments, the GaN-deposition chamber is furtherconfigured to dope the at least first GaN layer with silicon (Si).

In some embodiments, the present invention provides a gallium-nitridestructure that includes a template; and at least a first gallium nitride(GaN) layer grown on the template, wherein the at least first GaN layerhas an Omega rocking curve full-width half-maximum (FWHM) X-raydiffraction measurement for a 102 peak that is in a range of about 10arcseconds to about 2500 arcseconds. In some embodiments, the templateincludes an aluminum nitride (AlN) layer grown on a sapphire substrate,the structure further including a grown-epitaxial metal mirror (GEMM)grown on a surface of the at least first GaN layer, wherein the GEMMincludes alternating layers of hafnium (Hf):GaN and hafnium nitride(HfN); a layer of n-type GaN grown on a surface of the GEMM; and a layerof p-type GaN/multiple quantum wells (MQWs) grown on the layer of n-typeGaN.

It is specifically contemplated that the present invention includesembodiments having combinations and subcombinations of the variousembodiments and features that are individually described herein (i.e.,rather than listing every combinatorial of the elements, thisspecification includes descriptions of representative embodiments andcontemplates embodiments that include some of the features from oneembodiment combined with some of the features of another embodiment).Further, some embodiments include fewer than all the componentsdescribed as part of any one of the embodiments described herein. Stillfurther, it is specifically contemplated that the present inventionincludes embodiments having combinations and subcombinations of thevarious embodiments described herein and the various embodimentsdescribed by the related applications and publications incorporated byreference in paragraphs above of the present application.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Although numerous characteristics andadvantages of various embodiments as described herein have been setforth in the foregoing description, together with details of thestructure and function of various embodiments, many other embodimentsand changes to details will be apparent to those of skill in the artupon reviewing the above description. The scope of the invention shouldbe, therefore, determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein,” respectively. Moreover, the terms “first,” “second,” and“third,” etc., are used merely as labels, and are not intended to imposenumerical requirements on their objects.

What is claimed is:
 1. A method for growing a gallium nitride (GaN)structure comprising: providing a template having a surface; and growingat least a first GaN layer on the template using a first sputteringprocess, wherein the first sputtering process includes: growing the atleast first GaN layer under at least two surface conditions, wherein thetwo surface conditions include a gallium-rich surface condition and agallium-lean surface condition, wherein the gallium-rich surfacecondition includes a gallium-to-nitrogen ratio having a first value thatis greater than 1, wherein the gallium-lean surface condition includesthe gallium-to-nitrogen ratio having a second value that is less thanthe first value; alternating between the two surface conditions for atleast a first growing under a first of the two surface conditions, asecond growing under a second of the two surface conditions after thefirst growing, and a third growing under the first of the two surfaceconditions after the second growing.
 2. The method of claim 1, whereinthe alternating between the two surface conditions further includes afourth growing under the second of the two surface conditions after thethird growing, and a fifth growing under the first of the two surfaceconditions after the fourth growing.
 3. The method of claim 1, whereinthe at least first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for a 102 peak that isin a range of about 10 arc seconds to about 2500 arcseconds.
 4. Themethod of claim 1, wherein the first sputtering process further includesintroducing nitrogen via a radio frequency (RF) nitrogen source.
 5. Themethod of claim 1, wherein the first sputtering process further includesdoping the at least first GaN layer with silicon (Si).
 6. The method ofclaim 1, wherein the providing of the template includes growing analuminum nitride (AlN) layer on the template using a second sputteringprocess.
 7. The method of claim 1, further comprising growing agrown-epitaxial metal mirror (GEMM) on the at least first GaN layer. 8.The method of claim 1, wherein the first sputtering process furtherincludes doping the at least first GaN layer with germanium (Ge).
 9. Themethod of claim 1, wherein the first sputtering process further includesdoping the at least first GaN layer with hafnium (Hf).
 10. A method forgrowing a gallium nitride (GaN) structure comprising: providing atemplate; and growing at least a first GaN layer on the template using afirst sputtering process, wherein the first sputtering process includes:providing a gallium sputtering target, wherein the gallium sputteringtarget has a depth, and maintaining a temperature of the galliumsputtering target at a first temperature value that is less thanapproximately 14 degrees Celsius.
 11. The method of claim 10, whereinthe at least first GaN layer has an Omega rocking curve full-widthhalf-maximum (FWHM) X-ray diffraction measurement for a 102 peak that isin a range of about 10 arc seconds to about 2500 arcseconds.
 12. Themethod of claim 10, wherein the first sputtering process furtherincludes doping the at least first GaN layer with silicon (Si).
 13. Themethod of claim 10, wherein the maintaining of the temperature of thegallium sputtering target includes fluid-convection cooling the solidgallium target using an alcohol as a heat-transfer fluid.
 14. The methodof claim 10, wherein the growing of the at least first GaN layerincludes two-dimensional (2D) island growth.
 15. A method for growing agallium nitride (GaN) structure comprising: providing a template;growing a first aluminum nitride (AlN) layer on the template using afirst sputtering process; growing a first GaN layer on the first AlNlayer using a second sputtering process; growing a second AlN layer onthe first GaN layer using the first sputtering process; and growing asecond GaN layer on the second AlN layer using the second sputteringprocess.
 16. The method of claim 15, wherein the first GaN layer has anOmega rocking curve full-width half-maximum (FWHM) X-ray diffractionmeasurement for a 102 peak that is in a range of about 10 arcseconds toabout 2500 arcseconds.
 17. The method of claim 15, further comprising:growing one or more layers of Al_(x)Ga_((1-x))N on the second GaN layer,where x is between 0 and 1, inclusive.
 18. The method of claim 15,further comprising: growing one or more layers of Al_(x)Ga_((1-x))N onthe second GaN layer, where x varies with depth and is between 0 and 1,inclusive.
 19. The method of claim 15, further comprising: growing oneor more layers of compound on the second GaN layer, wherein the compoundincludes one or more selected from the group consisting of indiumnitride (InN), hafnium nitride (HfN), zirconium nitride (ZrN), aluminumnitride (AlN), gallium nitride (GaN), and scandium nitride (ScN). 20.The method of claim 15, wherein the first sputtering process furtherincludes doping the at least first GaN layer with silicon (Si).